Introduction to Atom
Atom is Intel's first processor aimed at the low power market; similar to how VIA introduced its C3 and C7 to take on these markets some time ago. The main aim for Atom is for the Mid, UMPC and HTPC environments; designed to consume as little power as possible while keeping some form of processing power onboard.
Atom is a new breed of CPU from Intel in that it is a totally new design. This is something interesting as we have seen that the Pentium-M processor was a re-design of the Pentium III processor, and even the Core 2 architecture has a lot of the Pentium-M in it. Atom is the first in-order processor to come out of the chip giant since the old 586 architecture, which makes it something you're not going to want to do media encoding on.
First off, let's have a look at the platform that each come in. The Atom is based around a mini-ITX motherboard layout, which is good for the industry. At Computex 2008 we were told that Intel was pushing for a new standard that was about 18 or 19cm rather than the 17x17 that mini-ITX runs. Somehow I don't think Intel wanted to be seen following VIA. Either way, though, it looks like either Intel either saw the light (not likely) or was pressured into using it by the big names out there who already have interest in mini-ITX. While they have given in on that part, Intel has given a huge amount of strict guide lines that companies have to follow to make an Atom based board.
First off, no digital components. What we mean by this is, simply, there is to be no digital video components such as DVI or HDMI output or digital audio outputs like Toslink or RCA S/PDIF. So, it's bye bye HTPC for this one.
Next is audio; only AC'97 audio is allowed. HD Azalia Audio is crossed out here. Lastly, only one memory slot is resident, making it hard to get any real performance out of it.
A testament to the power savings of the Atom is the single phase voltage regulation system that the CPU needs in order to get its power. Atom is extremely power efficient compared to any other Intel CPU ever made. The boards expansion system consists of a single PCI slot; there are no current generation slots available.
Now, let us introduce you to the Atom itself. This is what the CPU looks like under the heatsink. The Atom is extremely power efficient and therefore runs very cool; so cool in fact that it only requires passive cooling. We measured its temperature through our heat gun when under load; with the heatsink attached we saw it get to just 38c. That's extremely impressive.
Atom is the first in-order processor made from Intel since the Pentium 586 series. This processor is not aimed at breaking SuperPI world records; its aim is to try and replace VIA as the number one in energy efficient computing and hopefully steal some sales from VIA's embedded market.
The Atom comes clocked at 1.6GHz with a 533MHz FSB. The same bus used for the P4, Core 2 and even the C7 processor is used to increase the amount of data transfer between the CPU and MCH. 512K of L2 cache makes up the CPU on-die memory, which for a low power unit makes it extremely impressive.
While the Atom has only a single core, a familiar technology returns to help Atom make use of any un-used CPU cycles per clock. I am speaking of Hyper Threading. Those of us who remember the Pentium 4 processor will remember HT technology. This allows a single physical processor to be detected as two logical units, allowing more instructions per clock to be executed. As one instruction is leaving the CPU, the second doesn't have to be sent from memory to the data bus; it's already in the spare cycles being completed.
While you may think this CPU is cut down on features, it's far from the truth. Atom features SSE, SSE2 and SSE3 instruction sets along with EM64T, so yes, it can run Windows XP 64 and Vista 64, though how well it will do this is another thing.
All of this is produced on a 45nm High-K silicon die, the same transistors that make up the Penryn based Core 2 are used to give this CPU a TDP of 25 watts at max load.
Intel has chosen not to imbed a chipset into the CPU, so this is left to an external solution. What Intel has chosen to use is a rather outdated chipset by our standards. However, Intel doesn't want Atom to overshadow its high-end products. To this end, the i945GM chipset is given a re-birth as the Atom platform. The issue with this chipset is that it is quite power hungry for a system that Intel is aiming for low power consumption; it's said that the i945GM can use between 20 and 25watts, which is almost as high as the CPU itself. While the chipset can support dual channel memory, Intel is limiting this to single channel for Atom partners. Why they have done this is anyone's guess. Maybe Intel is waiting for something before opening its doors fully in this market segment.
The i945GM has the built-in GMA950 IGP. This is quite an old graphics system, even for the Intel standard which has now moved into the GMA X4500. First off, this IGP requires system memory and with only one memory slot, you're going to be losing between 64MB and 256MB, depending on how the dynamic memory system decides to deliver the memory around. With one slot, a max of 2GB memory is supported, so prepare for some system hits. Unfortunately, the GMA950 lacks any DX10 support as well as support for HD video decoding, so we will be interested to see just how well (or badly, I should say) it plays back some 720p and 1080p videos.
Accompanying the 945GM is the ICH7. This Southbridge may be aging but it still supports all the major features of today. There SATA-II interface is included for four ports, though only two are used on the Atom platform. HD Audio support is also there, but it's thrown out the window since AC'97 is the only option Intel allows. PCI-E lanes are also resident through the ICH7, but again we won't see that happening for some time. Finally, there's the inclusion of 10/100 Ethernet which is the only network standard allowed for Atom.
In all, Intel has really set the Atom back with its limited hardware choices.