AMD's Radeon HD 6990: The New Single Card King
by Ryan Smith on March 8, 2011 12:01 AM EST- Posted in
- AMD
- Radeon HD 6990
- GPUs
PCI-Express Compliance: Does It Even Matter?
For a while now we’ve been under the impression that video card size and power consumption was ultimately capped by the PCI-Express specification. At present time the specification and its addendums specify normal (75W), 150W, 225W, and 300W PCIe card operation. In the case of 300W cards in particular this is achieved through 75W from the PCIe slot, 75W from a 6pin PCIe power connector, and 150W from an 8pin PCIe power connector. As the name implies, the PCIe specification also defines what the 6pin and 8pin power connectors are supposed to be capable of, which is where 75W and 150W come from respectively.
Altogether the biggest, most powerful card configuration in the PCIe specification allows for a 12.283” long, triple-wide card that consumes 300W. To date we’ve never seen a card exceed the physical specifications, but we’ve seen several cards exceed the electrical specifications. This includes cards such as the 5970 and some overclocking-oriented 5870s that were designed to handle more than 300W when overclocked, and even more exotic cards such as the Asus ARES 5870X2 that simply drew more than 300W from the get-go. We have yet to see a reference design from AMD/NVIDIA however that exceeds any part of the PCIe specification by default.
So it has been clear for some time now that cards can exceed the PCIe specifications without incurring the immediately wrath of an army of lawyers, but at the same time this doesn’t establish what the benefits or losses are of being or not being PCIe compliant. To have a reference design exceed the PCIe specifications is certainly a new mark for the GPU industry, so we decided to get right to the bottom of the matter and get an answer to the following question: does PCI-Express compliance matter?
To answer this question we went to two parties. The first of which was of course AMD, whose product is in question. AMD’s answer basically amounts to a polite deflection: it’s an ultra-enthusiast card that at default settings does not exceed the power available by the combination of the PCIe slot and PCIe power connectors. Furthermore, as they correctly note, the 6990 is not the first card to ship at over 300W, as the ARES and other cards were drawing more than 300W a year ago. It’s a polite answer that glosses over the fact that no, the 6990 isn’t technically PCIe compliant.
To get a second opinion on the matter we went straight to the source: The Peripheral Component Interconnect Special Interest Group (PCI-SIG), which is the industry group that defines the PCIe standard and runs the workshops that test for product compliance. The PCI-SIG’s member list is virtually everyone in the computing industry, including AMD, NVIDIA, and Intel, so everyone has some level of representation with the group.
So what does the PCI-SIG think about cards such as the 6990 which exceed the PCIe specification? In a nutshell, they don’t directly care. The group’s working philosophy is closer to approving cards that work than it is about strictly enforcing standards, so their direct interest in the matter is limited. The holy grail of the PCI-SIG is the PCI Express Integrators List, which lists all the motherboards and add-on cards that have passed compliance testing. The principal purpose of the list is to help OEMs and system integrators choose hardware, relying on the list and by extension PCI-SIG testing to confirm that the product meets the PCIe standards, so that they can be sure it will work in their systems.
The Integrators List is more or less exclusively OEM focused, which means it has little significance for niche products such as the 6990 which is split between end-user installation and highly customized OEM builds. The 6990 does not need to be on the list to be sold to its target market. Similarly the 5970 was never submitted/approved for listing, and we wouldn’t expect the 6990 to be submitted either.
It is worth noting however that while the PCI-SIG does have power specifications, they’re not a principal concern of the group and they want to avoid doing anything that would limit product innovation. While the 300W specification was laid out under the belief that a further specification would not be necessary, the PCI-SIG does not even test for power specification compliance under their current compliance testing procedures. Conceivably the 6990 could be submitted and could pass the test, leading to it being labeled PCIe compliant. Of course it’s equally conceivable that the PCI-SIG could start doing power compliance testing if it became an issue…
At the end of the day as the PCI-SIG is a pro-compliance organization as opposed to being a standard-enforcement organization, there’s little to lose for AMD or their partners by not being compliant with the PCIe power specifications. By not having passed compliance testing the only “penalty” for AMD is that they cannot claim the 6990 is PCIe compliant; funny enough they can even use the PCIe logo (we’ve already seen a Sapphire 6990 box with it). So does PCIe compliance matter? For mainstream products PCIe compliance matters for the purposes of getting OEM sales; for everything else including niche products like the 6990, PCIe compliance does not matter.
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iamezza - Tuesday, March 8, 2011 - link
This could make for an extremely valuable article for gamers on a budget. When does lack of PCIe bandwidth become an issue for running SLI/crossfire?Testing 580SLI at 2 x 8 and 2 x 16 modes would be a good place to start....
therealnickdanger - Tuesday, March 8, 2011 - link
It will be curious to see what impact the bandwidth will have... then again, even with the restriction, the current Sandy Bridge systems still dominate the previous chips.In reality, 16/16 or 8/8 really doesn't have much impact. The difference even at 2560x1600 with all the fixins in even the most demanding games is <1%. Unless AT's new test system will feature six displays and 4K+ resolutions, I'm not sure SNB-E is worth waiting so long for (yes, that could be perceived as a challenge!)
In any case, I'm looking forward to it! Thanks for the article!
shaggart5446 - Tuesday, March 8, 2011 - link
i hope u said the same thing when ur friend nvidia release their 590 card i also do hope u say the exact words that the 590 dont make any sence since a pair of 560 or 570 can give u the same performance as the 590 i cant wait to see ur article on the 590 ill be waiting for anand tfor this because we all know that the 590 are going to be down clockClownPuncher - Tuesday, March 8, 2011 - link
With cards designed specifically with multi monitor gaming in mind, you may want to include those resolutions. Buying this card for 1920x1200 would make zero sense.7Enigma - Wednesday, March 9, 2011 - link
I think it was good to have both. The number of people buying this card will likely have 30" displays, but I'm sure some (competetive FPS for example) will want extremely fluid display even in busy scenes, as well as the person that doesn't yet have the cash to upgrade to a big screen but plans to in the near future.I would also argue that there are likely vastly more people playing on large single-screen displays than eyefinity folks so this does make more sense. And honestly when some of the games are averaging in the sub 80-100 fps range, those minimum framerates approach questionable playability depending on type of game.
So basically as crazy as it is to say this, the graphical power isn't quite there yet to use Eyefinity at high detail settings in more recent and demanding games.
Nentor - Tuesday, March 8, 2011 - link
"With but a trio of exceptions, the 6990 doesn’t make sense compared to a pair of cards in Crossfire."This product is not meant to make any sense from a financial, performance or even practical standpoint.
It IS the fastest videocard and that is that.
I was watching a video last night on youtube of a chainsaw powered by a Buick's V8 engine (hG5sTLY0-V8). It goes through a tree trunk in a blink of an eye, but it had to be lifted by TWO men.
Sure is cool though.
Squuiid - Sunday, March 13, 2011 - link
It makes complete sense if you want SLI in a small form factor, mATX and such. (as do I).PCIe slots are at a premium, and so is space on a mATX board/case.
However, I think I'm going to wait and see what the 590 looks like...
Fhistleb - Tuesday, March 8, 2011 - link
I didn't even think that was possible. Though with what this is pushing out its a little expected I suppose.stangflyer - Tuesday, March 8, 2011 - link
I would like to see the 6990 and 5970 comparison in crysis and metro at eyefinity and single monitor res but with the 5970 at default clocks and close to 5870 clocks. When I am playing these games I have my 5970 at 850 core and 1150 memory and it runs all day without any throttling.The 5970 is handicapped at the default speeds as everyone can run at or real close to 5870 speeds. The core is easy at 850 but you may need to back down memory to 1150 or 1175.
Would love to see the true difference in the 5970 and 6990 this way.
The framebuffer will be the big difference at eyefinity res. with any aa applied.
stangflyer - Tuesday, March 8, 2011 - link
One thing I do like about the dual gpu amd cards is that I play a few games that use physx.. (I have a 5970) I have a 250gts in the second pcie slot. both my slots are 2x16. This way I have a powerfull gpu and physx! I play my games at 5040x1050 and a single card just don't cut it. I did use nvidia surround for 2 months but like my eyefinity setup better. To go crossfire and then have physx you need a motherboard that doesn't knock your pcie slot down to 8x with 3 cards which are few and expensive and also a case that has space for that 3rd card like a coolermaster haf 932X. I have a haf 932 (not X) and I could not go 3 cards unless the 3rd card is single slot.On a side note as to why I am sticking with my 5970 till the 28nm show up is that I like the way the cooler is set up. With the fan on the end I have my 250gts below it with about a 3/8 inch below it. BUT the 250gts is only about 7.5-8 inches long and does not cover the fan at all because the fan is at the end. I have a 120mm fan at the bottom of my haf 932 case that blows straight up into the 5970 fan.
If I used a 6990 the 250gts would cover the 6990 fan.
My choices would be then to sell the 250gts and get a single slot card. (450gts probably)
I think I am just going to stay with what I have for now.
Maybe! LOL!