MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review

The fastest single GPU card on the market gets a little faster thanks to MSI. Whats this Lightning version offer us?

Published
Updated
Manufacturer: MSI
16 minutes & 43 seconds read time

Introduction and Package


Introduction

MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 02


If you, like us were impressed with what the MSI HD 6970 Lightning offered which we looked at just the other day here, yet you're happy to spend some more to jump on the fastest single GPU card on the market, then we might just have the card for you.

Kicking it up a notch in price and performance, the MSI GTX 580 Lightning could well be the card for you, being of course based on the high end GTX 580 GPU. The Lightning series is all about overclocking, though, so we want to find out just what this series can do for the GTX 580.

Before we get into all the fun stuff, though, let's first check out the package. Once that's done we'll have a look at the card itself and the overclock we managed to achieve. Then we'll of course get into the performance side of things to see exactly what the MSI GTX 580 Lightning is able to offer.


Package

MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 03


MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 04


MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 05


Looking at the bundle, we've of course got that typical Lightning bundle on offer which offers the normal VGA extras like paperwork, driver CD and DVI to VGA connector. We've also got two 6-Pin to 8-Pin PCI-E power connectors, three voltage measuring cables and two extra-long SLI connectors.

Card and Specifications


The Card

MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 06


Looking at the card, it's very similar to the HD 6970 Lightning we just looked at with the Twin Frozr III cooler taking up the majority of the card. It's a very mean looking cooler with a copper base, a number of heat pipes and that dual fan setup.

MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 07


MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 08


Looking across the top, we've got some familiar sightings; power is provided by two 8-Pin PCI-E power connectors and in the center we've got three little ports that are used to measure voltage for the Core, AUX and Memory. This is done via the connectors included in the box and a volt meter.

MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 09


Closer to the front of the card we've got our two SLI connectors and just next to that we've got a switch similar to what we've seen on higher end AMD cards and the Lightning HD 6970 we just looked at. While the HD 6970 switch helped unlock the OC potential of the card by removing the limit on core and memory....

MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 10


....on the GTX 580 the switch allows use of a different BIOS which comes in handy if you're going to do extreme overclocking with the help of LN2. What can happen is when a card moves into the negative temperature range, it can think it's overheating and shut down or lower the clocks. The "LN2 BIOS" helps prevent this. On the other side of the fence, if something goes wrong while flashing your BIOS you've also got a backup which will help restore the original BIOS.

MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 11


On the connectivity side of things we've got two Dual-Link DVI connectors along with a single HDMI and DisplayPort connector.


Specifications

The MSI GTX 580 Lightning of course comes overclocked out of the box and we see it move from a 772MHz Core which offers a 1544MHz Shader clock to a 832MHz core and 1664MHz Shader clock. MSI has also upped the 1536MB of GDDR5 from 4008MHz QDR too 4200MHz QDR.

MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 01


The Lightning series is all about overclocking, though, and we pushed the core up almost another 100MHz to 930MHz. That in turn pushed the Shader clock to 1860MHz. From the reference 772MHz / 1544MHz setup this is a really nice overclock.

As for the memory, we pushed that another 400MHz QDR which resulted in a memory speed of 4600MHz QDR. This is a very strong overclock and should yield some great performance when compared to the reference GTX 580.

Test System Setup and 3DMark 11


MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 99


We would like to thank the following companies for supplying and supporting us with our test system hardware and equipment: Intel, ASRock, Kingston, Mittoni, Noctua and Corsair.

We'll be looking at the MSI GTX 580 Lightning @ 930MHz / 4600MHz QDR against the reference MSI GTX 580, Palit GTX 560 Ti in SLI and ASUS GTX 590. For AMD we've got the reference HD 6970, HD 6950 2GB in CF and HD 6990.

We've also included the MSI HD 6970 Lightning @ 1015MHz / 6260MHz QDR. These are much higher numbers than the NVIDIA GTX 580 Lightning we're looking at today, but as we know speed isn't always just about the clocks that are on offer, so it will be interesting to see how this Lightning card goes against that one.

Let's get started!


3DMark 11

Version and / or Patch Used: 1.0
Developer Homepage: http://www.futuremark.com
Product Homepage: http://www.3dmark.com/3dmark11/
Buy It Here




3DMark 11 is the latest version of the world's most popular benchmark. Designed to measure your PC's gaming performance 3DMark 11 makes extensive use of all the new features in DirectX 11 including tessellation, compute shaders and multi-threading. Trusted by gamers worldwide to give accurate and unbiased results, 3DMark 11 is the best way to consistently and reliably test DirectX 11 under game-like loads.

MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 20


Straight away we fire up 3DMark 11 and we've got some very good performance; a very good increase over the reference GTX 580 and you can see the card has no problems convincingly holding on to top single GPU honors.

3DMark Vantage




Version and / or Patch Used: 1.0.1
Developer Homepage: http://www.futuremark.com
Product Homepage: http://www.futuremark.com/products/3dmarkvantage/
Buy It Here




3DMark Vantage is the new industry standard PC gaming performance benchmark from Futuremark, newly designed for Windows Vista and DirectX10. It includes two new graphics tests, two new CPU tests, several new feature tests, and support for the latest hardware.

3DMark Vantage is based on a completely new rendering engine, developed specifically to take full advantage of DirectX10, the new graphics API from Microsoft.

MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 21


3DMark Vantage performance is very strong, but as we've mentioned a bit lately it will be removed in our next benchmark refresh in the next few weeks.

Unigine Heaven Benchmark




Version and / or Patch Used: 2
Developer Homepage: http://www.unigine.com
Product Homepage: http://unigine.com/press-releases/091022-heaven_benchmark//



New benchmark grants the power to unleash the DirectX 11 potential in the gift wrapping of impressively towering graphics capabilities. It reveals the enchanting magic of floating islands with a tiny village hidden in the cloudy skies. With the interactive mode emerging experience of exploring the intricate world is ensured within reach. Through its advanced renderer, Unigine is one of the first to set precedence in showcasing the art assets with tessellation, bringing compelling visual finesse, utilizing the technology to the full extend and exhibiting the possibilities of enriching 3D gaming.

MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 22


Looking at Heaven we see some strong performance again and we continue to see the domination that NVIDIA have in these tessellation heavy environments.

Benchmarks - Resident Evil 5


Resident Evil 5

Version and / or Patch Used: Demo Benchmark
Developer Homepage: www.residentevil.com/
Product Homepage: http://www.residentevil.com/




Resident Evil 5 is a survival horror video game developed and published by Capcom. The game is the seventh installment in the Resident Evil survival horror series, and was released on September 18. Resident Evil 5 revolves around Chris Redfield and Sheva Alomar as they investigate a terrorist threat in Kijuju, a fictional town in Africa.

MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 23


Resident Evil 5 sees a bit increase in performance across the board, but we've already got playable numbers, so that's something worth noting.

Benchmarks - Tom Clancy's H.A.W.X. 2


Tom Clancy's H.A.W.X.2

Version and / or Patch Used: Benchmark Demo
Timedemo or Level Used: Built-in Test
Developer Homepage: http://www.ubi.com/UK/default.aspx
Product Homepage: http://www.hawxgame.com/




Tom Clancy's H.A.W.X. 2 is an arcade-style flight action game developed by Ubisoft Romania and published by Ubisoft. The game is the sequel to Tom Clancy's H.A.W.X., released in 2009.

The game begins with Colonel David Crenshaw participating in a routine patrol mission in the Middle East. After halting an insurgent attack, a volley of missiles is fired at the Air Force base that Crenshaw was stationed at, with one of the missiles disabling Crenshaw's aircraft, resulting Crenshaw being in enemy captivity. A joint strike force composed of the U.S. Navy, U.S. Air Force, and a Ghost Recon squad executes an operation to rescue Crenshaw. In Scotland, Royal Navy Pilot Colin Munro encounters an unidentified passenger aircraft that explodes from an on-board bomb when undergoing training exercise. In Russia, an air force squadron led by Colonel Denisov and Captain Dmitri Sokov engages separatist aircraft but is ordered to retreat from the region after numerous Russian military installations have been attacked.

MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 24


We know HAWX 2 indeed favors the NVIDIA offerings, but here we've just got some blistering performance from the card again. Near 200 FPS at 2560 x 1600 in this great looking game just shows the amount of power that's on offer.

Benchmarks - Mafia II


Mafia II

Version and / or Patch Used: Latest Steam Update
Timedemo or Level Used: Built in Benchmark
Developer Homepage: http://www.2kczech.com/
Product Homepage: http://www.mafia2game.com/
Buy It Here




Mafia II is a third-person action-adventure video game, the sequel to Mafia: The City of Lost Heaven. It is developed by 2K Czech, previously known as Illusion Softworks, and is published by 2K Games. The game is set from 1943 to 1951 in Empire Bay (the name is a reference to New York's state nickname "The Empire State"), a fictional city based on San Francisco and New York City, with influences from Chicago and Detroit. The game features a completely open-ended game map of 10 square miles. No restrictions are included from the start of the game. There are around 50 vehicles in the game, as well as licensed music from the era.

MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 25


Mafia II performance is great. We continue to see a strong boost in performance, but the 2560 x 1600 numbers are the most important. We aim for an average of 60 FPS and that's what we know will create a smooth gaming experience. When you're just around that mark, though, it's nice to get a little further away.

Overclocked, you can see our Lightning card jumps more than 10 FPS and that's going to make sure your gaming experience is silky smooth at this resolution.

Benchmarks - Lost Planet 2


Lost Planet 2

Version and / or Patch Used: Benchmark Demo
Timedemo or Level Used: Built in Benchmark - Test A Scene 1
Developer Homepage: http://www.capcom.com/
Product Homepage: http://www.lostplanet2game.com/




Lost Planet 2 is a third-person shooter video game developed and published by Capcom. The game is the sequel to Lost Planet: Extreme Condition which is also made by Capcom, taking place ten years after the events of the first game, on the same fictional planet. The story takes place back on E.D.N. III 10 years after the events of the first game. The snow has melted to reveal jungles and more tropical areas that have taken the place of more frozen regions. The plot begins with Mercenaries fighting against Jungle Pirates. After destroying a mine, the Mercenaries continue on to evacuate the area, in which a Category-G Akrid appears and attacks them. After being rescued, they find out their evacuation point (Where the Category-G appeared) was a set-up and no pick up team awaited them. The last words imply possible DLC additions to the game, "There's nothing to be gained by wiping out snow pirates... unless you had some kind of grudge."

MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 26


Lost Planet 2 is very tessellation heavy and you can see that NVIDIA performs very strong here because of that. We've got some strong performance gains again from the Lightning version. At 2560 x 1600 we're almost at the number we need to be, but fall just a little behind. A minor detail drop from that "Very High" preset we use will help push the numbers up to a level we would comfortably say is playable.

Benchmarks - Aliens vs. Predator


Aliens vs. Predator

Version and / or Patch Used: Standalone Benchmark
Timedemo or Level Used: Built in Benchmark
Developer Homepage: http://www.rebellion.co.uk/
Product Homepage: http://www.sega.com/games/aliens-vs-predator/




Aliens vs. Predator is a science fiction first-person shooter video game, developed by Rebellion Developments, the team behind the 1999 original PC game, and published by Sega for Microsoft Windows, the PlayStation 3 and the Xbox 360. The game is based on the Alien vs. Predator franchise, a combination of the characters and creatures of the Alien franchise and the Predator franchise. There are three campaigns in the game, one for each race/faction (the Predators, the Aliens and the Colonial Marines), that, while separate in terms of individual plot and gameplay, form one overarching storyline.

Following the storyline of the campaign modes comes the multiplayer aspect of the game. In this Multiplayer section of the game, players face off in various different gametypes in various different ways.

MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 27


Aliens vs. Predator offers some great performance, but you can see to achieve a 60 FPS average at 2560 x 1600 you need a dual GPU setup. 1920 x 1200, though, performance is silky smooth and we've got an increase of almost over 10% when compared to the reference card.

Benchmarks - Street Fighter IV


Street Fighter IV

Version and / or Patch Used: Standalone Benchmark
Timedemo or Level Used: Built in Benchmark
Developer Homepage: http://www.capcom.com/
Product Homepage: http://www.streetfighter.com/




While Street Fighter IV features models and backgrounds rendered in 3D, the gameplay remains on a traditional 2D plane, with the camera having freedom to move in 3D at certain times during fights, for dramatic effect. Producer Yoshinori Ono has stated that he wanted to keep the game closer to Street Fighter II. A new system called "Focus Attacks" ("Saving Attack" for the Japanese version) has been introduced, as well as Ultra moves. The traditional six-button control scheme returns, with new features and special moves integrated into the input system, mixing classic gameplay with additional innovations.

All the characters and environments in Street Fighter IV are rendered as 3D models with polygons, similar to the Street Fighter EX sub-series Capcom produced with Arika. However, there are a couple of key differences. Art director and character designer Daigo Ikeno, who previously worked on Street Fighter III 3rd Strike, opted for non-photorealistic rendering to give them a hand-drawn look, with visual effects accented in calligraphic strokes, ink smudges and ink sprays during the fights.

MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 28


No surprise under SF IV with the numbers we're seeing. It's probably a little bit of a useless benchmark, but it's nice to see something run at 400 FPS in real time.

Benchmarks - Far Cry 2


Far Cry 2

Version and / or Patch Used: 1.01
Timedemo or Level Used: Ranch Long
Developer Homepage: http://www.ubi.com/
Product Homepage: http://www.farcry2.com/
Buy It Here




The Dunia Engine was built specifically for Far Cry 2 by the award-winning Ubisoft Montreal development team. It delivers the most realistic destructible environments, amazing special effects such as dynamic fire propagation and storm effects, real-time night-and-day cycle, dynamic music system, non-scripted enemy A.I. and so much more.

MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 29


Under Far Cry 2 we see some strong performance gains over the reference card. You may find yourself asking, though, what's the benefit to having such huge FPS when you can only see so much. If you get on a 120Hz LCD, turn V-Sync on and can achieve an average of around 120 FPS, your gaming experience will just be silky smooth.

Benchmarks - Batman Arkham Asylum


Batman Arkham Asylum

Version and / or Patch Used: 1.1
Timedemo or Level Used: Built-in Test
Developer Homepage: http://www.batmanarkhamasylum.com/
Product Homepage: http://www.batmanarkhamasylum.com/





Batman: Arkham Asylum exposes players to a unique, dark and atmospheric adventure that takes them to the depths of Arkham Asylum - Gotham's psychiatric hospital for the criminally insane. Gamers will move in the shadows, instigate fear amongst their enemies and confront The Joker and Gotham City's most notorious villains who have taken over the asylum.

Using a wide range of Batman's gadgets and abilities, players will become the invisible predator and attempt to foil The Joker's demented scheme.
Batman: Arkham Asylum features an original story penned exclusively for the game by famous Batman author and five-time Emmy award winner Paul Dini, whose credits include Lost season one and Batman: The Animated Series.

MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 30


Batman AA just offers some massive performance and you can see a nice jump in the averages. It's probably not so needed considering the numbers we're dealing with, but it's nice to see higher performance nonetheless.

Benchmarks - High Quality AA and AF


High Quality AA and AF

Our high quality tests let us separate the men from the boys and the ladies from the girls. If the cards weren't struggling before they will start to now.

MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 31


MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 32


MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 33


MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 34


Apart from Aliens vs. Predator that falls a little shy, we've got some very good performance when we crank up the detail, which is exactly what you expect when buying such a high end card.

Benchmarks - PhysX Tests


PhysX Tests

Here we're able to find out when PhysX is turned on in games that support it what kind of frame rates we're able to get. We always set PhysX to the highest possible in game settings while also keeping detail at its highest.

MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 35


MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 36


While Batman AA performance is strong, you can see setups that don't have a dedicated card for PhysX do indeed struggle under Mafia II. As good as PhysX is, it just hasn't taken off yet and isn't a major selling point for people when buying a card. Instead, the raw power is, and NVIDIA do a good job with that.

Temperature Test


Temperature Tests



The temperature of the core is pulled from MSI Afterburner with the max reading used after a completed run off 3DMark Vantage and the Performance preset.

MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 40


Considering all the extra voltage we're running through the card, the temperature is still very good. The GTX 580 does indeed run warmer than the HD 6970 Lightning, but that's not a surprise. The main thing is we're not running too hot and you can see we're not with cards running up to 20c hotter in some situations.

Sound Test


Sound Tests



Pulling out the TES 1350A Sound Level Meter we find ourselves quickly yelling into the top of it to see how loud we can be.

After five minutes of that we get a bit more serious and place the device two CM away from the fan on the card to find the maximum noise level of the card when idle (2D mode) and in load (3D mode).

MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 41


The card actually manages to get quite noisy at times under full load. What's interesting, though, is that while the noise is indeed quite loud, it's more of a "hum" vs. a "whine." That will probably not make a lot of sense to people, but if you've dealt with smaller fans that offer a more high pitch noise, you probably do get what I'm getting at.

The "hum" the GTX 580 Lightning has is much easier on the ears vs. the noise a HD 6990 makes. The fact the HD 6990 also fluctuates a lot is annoying as well, as your ears never adjust.

Power Consumption Tests






Using our new PROVA Power Analyzer WM-01 or "Power Thingy" as it has become quickly known as to our readers, we are now able to find out what kind of power is being used by our test system and the associated graphics cards installed. Keep in mind; it tests the complete system (minus LCD monitor, which is plugged directly into AC wall socket).

There are a few important notes to remember though; while our maximum power is taken in 3DMark06 at the same exact point, we have seen in particular tests the power being drawn as much as 10% more. We test at the exact same stage every time; therefore tests should be very consistent and accurate.

The other thing to remember is that our test system is bare minimum - only a SSD hard drive is used with a single CD ROM and minimal cooling fans.

So while the system might draw 400 watts in our test system, placing it into your own PC with a number of other items, the draw is going to be higher.

MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 42


Power draw is high and indeed it's the highest single GPU card; just over 500 watt, though, isn't a big problem and if you're buying such a high end card you should already have, or at least be buying a good high end 850 Watt+ PSU at the same time.

Total Performance Rating (TPR)


Total Performance Rating

The TPR graph is a combination of all our benchmarks in which NVIDIA and AMD are on an even playing field.

The TPR number is a combination of:

3DMark 11, Heaven Benchmark V2, Resident Evil 5, Tom Clancy's H.A.W.X.2, Mafia 2 (PhysX Off), Lost Planet 2, Aliens vs. Predator, Street Fighter IV, Far Cry 2, Batman: Arkham Asylum (PhysX Off) and our four High Quality tests which include Mafia 2, Aliens vs. Predator, Street Fighter IV and Far Cry 2.

All of the benchmark results achieved are then combined into a single number. As this graph will grow over time and cards won't be re-tested, next to each model you'll find the driver version that was used when the card was benchmarked.

MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 50


It comes as no surprise the amount of power that is on offer from this GTX 580 from MSI. While priced higher than the HD 6970 version, it indeed offers more performance and you can see it's able to outperform even the HD 6850 in CrossFire and isn't all that far behind the HD 6870 in CrossFire.

Total Value Rating (TVR)


Total Value Rating

The TVR graph is the TPR score divided by the price of the video card. The price of the video card is based on the list price of the model on Newegg.com. In the event the card isn't listed, it will be based on the U.S. $ MSRP given to us by the manufacturer.

In the event we can't source a price from either, the product will not receive a TVR rating. As with our TPR graph, the amount of video cards on the list will grow over time and the price of the model won't change from what it was when first reviewed. For this reason the U.S. $ price that the card is based off will be included next to the name of the model.

In the event you want to find the TVR rating yourself based on the current price, all you have to do is simply divide the TPR number by the list price.

TVR numbers are rounded to the nearest whole number; 100.3 will be 100; 100.8 will be 101 and 100.5 will be rounded down to 100.

MSI GeForce GTX 580 1536MB Lightning Overclocked Video Card Review 51


The $500+ price tag is indeed a big jump over the AMD version of the card, but it's not a big surprise as when we get more performance on these higher end cards the overall value does indeed tend to drop. Of course, this just tells us the value in a pure FPS you get to cost of the card. If you want the fastest single GPU card, then its value is enormous too you.

Final Thoughts




At $519 US you just need to ask yourself one question. Do you want the fastest single GPU card available? If the answer to that is "Yes", then this is the card for you. The GTX 580 is fast; when overclocked it's faster again. Overclocked even more due to the extra abilities you get from the "Lightning" series and you've just got a card that's Lightning fast. Excuse the lame pun!

Something that's so important to know about the Lightning series is while MSI put a huge amount of effort into making them the best cards for people who are doing extreme overclocking via LN2, they're a fantastic card for people who are just interested in overclocking on the cooler.

The ability to have more voltage options means that clocks can go higher than other cards, and in the software MSI allow only options that are safe on the solution they provide. Combined with Afterburner you can have a real blast with the Lightning series on the provided coolers. The fact they're also a lot more efficient than the reference coolers means that the headroom for overclocking is also increased.

The HD 6970 Lightning is a better value card; it's cheaper and offers great performance. The GTX 580 Lightning is a faster card, though; it costs more, but offers more performance. For people who demand speed, this is the card to get and while dual GPU offerings like the GTX 590 and HD 6990 are great, if you've got the room and the money, SLI or CrossFire offerings of these Lightning cards are going to be even better.

Don't be scared off by the ability to measure voltage from the card or the "LN2" BIOS, because as we mentioned, while this is a fantastic card for those extreme overclockers, the engineering that goes into this card, the out of the box cooling solution and the ability to adjust multiple voltages also makes this a fantastic card for people who will use the stock cooler.

What do TweakTown.com awards mean? Click for details!

PRICING: You can find products similar to this one for sale below.

USUnited States: Find other tech and computer products like this over at Amazon.com

UKUnited Kingdom: Find other tech and computer products like this over at Amazon.co.uk

AUAustralia: Find other tech and computer products like this over at Amazon.com.au

CACanada: Find other tech and computer products like this over at Amazon.ca

DEDeutschland: Finde andere Technik- und Computerprodukte wie dieses auf Amazon.de

Shawn takes care of all of our video card reviews. From 2009, Shawn is also taking care of our memory reviews, and from May 2011, Shawn also takes care of our CPU, chipset and motherboard reviews. As of December 2011, Shawn is based out of Taipei, Taiwan.

Newsletter Subscription
We openly invite the companies who provide us with review samples / who are mentioned or discussed to express their opinion. If any company representative wishes to respond, we will publish the response here. Please contact us if you wish to respond.