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Gigabyte GeForce 6600GT - An AGP Alternative

By: Cameron Johnson | NVIDIA GeForce GPU in Video Cards | Posted: May 3, 2005 4:00 am
TweakTown Rating: 9.0%Manufacturer: Gigabyte

Specifications of the GV-NT66GT-128D


GPU/VIP: nVidia GeForce 6600GT GPU


Bus: AGP Bridged through HSI Bridge


Graphics Bus: 128bit


Memory: 128MB GDDR3


Memory Bus: 128bit


Monitor Connections: 1x 15pin D-Sub. 1x DVI-I Digital Interface


TV Support: HDTV, S-Video, RCA output through selector box


Supports Multiple Monitors: Yes (nVidia nView)


Hardware Monitor Support: Yes


Software Bundle: 1 Game + Power DVD.


Core Clock: 500Mhz


Memory Clock 900Mhz (450Mhz DDR)


The Card and Package



Gigabyte packs their 6600GT AGP edition in a very similar box to what the PCI-E version ships; however, on the front and back it clearly states this version is AGP, so no confusion should arise when purchasing the card in a retail shop.


Inside the board a very liberal package in supplied, as Gigabyte wants to keep the cost of the card down as much as possible. Inside you get your user manual, Driver CD, full game CD (varies depending on what revision of the card you get), Power DVD 5 CD, TV breakout box and power splitter cable.



These days it is very hard to find a graphics card that differs from the reference design that nVidia or ATI set out. Gigabyte has based the 6600GT AGP edition around the reference design for two reasons. 1) Trusted and stable layout and 2) no R&D needs to go into the card for PCB layout changes, keeping costs to a minimum for production. The PCB though is a blue colour rather than the green used by nVidia for reference.


The coolers used are designed by Gigabyte for a slightly better thermal dissipation of heat. The cooler on the GPU is angled due to the layout of the GPU chipset. Below that a smaller passive cooler is attached to the HSI bridge in order to keep this little fellow running at a safe temperature. While it appears the two coolers are connected they are both separated. A nice idea would be a cooler that fits on both to actively cool the HSI and GPU. With the coolers removed you can see how closely the card resembles the reference design. Being an AGP based card, there is no support for SLI due to the lack of dual AGP based boards.



The driving force is the nVidia GeForce 6600GT. This chip has become one of the biggest sellers in the mid-range market. Able to hold its own against the ATI X700 series with the ability to pair up with an additional 6600GT (PCI-E only) to increase the graphics performance, its no wonder that the 6600GT is making a good name for itself.



Memory wise, the same Samsung 2ns BGA G-DDR3 chips which power Gigabyte's PCI-E 6600GT and nVidia reference card are used. These chips are able to handle speeds up to and beyond 1GHz, so overclocking on this card via memory should be just as good as the Gigabyte PCI-E version.


- Changes from the PCI-Express edition


Due to the 6600GT being a native PCI-E solution, nVidia needed to convert the signals that the GPU produces into AGP. Fortunately the HSI bridge chip was sitting on the back lot with nVidia which was originally designed to convert AGP based video cards over to PCI-E during the beginning of the PCI-E era. The PCX series that the chip was used on was avoided like the plague due to stability problems trying to run the AGP based chips at speeds beyond their rated maximum. However, this chip could be used to convert the faster PCI-E back to AGP without having to overclock buses, which is what nVidia has done, allowing its PCI-E based GPU's to run seamlessly on AGP systems with one simple bridge. The HSI bridge needs to be cooled by a heatsink as running the buses through this small chip does tend to make it quite hot to the touch, a joint cooler with the GPU for active cooling would have been a better idea.



This is definitely a difference between the AGP and PCI-E versions. Based on a PCI-E bus, the 6600GT doesn't require an additional power connector. This is because of the revised power draw that the PCI-E can deliver. On the PCI-E bus, up to 75 watts is available to the video card, whereas on AGP 45 watts is the maximum that any card can draw. Obviously the 6600GT fits in the middle here as a 4 pin Molex connector appears on the AGP edition where no additional power is needed on Gigabyte PCI-E edition.




We are pleased to report a great overclocking experience with this card. Being based on many of the PCI-Express based components, we were expecting to see speeds comparable to the PCI-E based cards. We managed to not only hit the PCI-E default clock speeds but exceed them.


Coolbits was used to unlock the overclocking control panel in the Foreware drivers. With a default core clock of 500MHz and memory clock of 900MHz DDR, we managed to hit 720MHz on the core and 1.2GHz on the memory - the exact same as our PCI-E version reached - which is an excellent result.


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