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
Final Thoughts
Wrapping things up, there’s little we need to say that wasn’t already evident in our graphs. The 6990 is a halo card and succeeds at such – by packing two Cayman GPUs on a single card, it is without question the fastest video card on the market today. At the same time there is and always will be a distinction between single-GPU cards and dual-GPU cards; the former is a threat to the latter, but the latter is rarely a threat to the former.
When we reviewed the Radeon HD 5970 back in 2009, the principle question we ran in to was whether it would be better to have a 5970 or two 5850s in CrossFire, given that the two were nearly identical in performance. The answer was that CrossFire was superior so long as you had a power supply with four readily available PCIe power plugs. With the Radeon HD 6990, we find ourselves asking the same question and an even more direct answer. With but a trio of exceptions, the 6990 doesn’t make sense compared to a pair of cards in CrossFire.
The reasons for this are numerous. The 6990 is so close to the 6950CF in performance that on average at 2560 the two are identical. It’s only in Bad Company 2 and Stalker that we see the 6990 take an advantage, which is then negated by anything from Civilization V to DIRT 2. Meanwhile the 6950CF is cooler, significantly quieter, and less power hungry than the 6990. And finally the 6950CF is cheaper: we can snag a pair of cards for $520, versus $700 for the 6990. Likewise, for $640 you can have a pair of 6970s and enjoy performance at 2560 roughly 8% ahead of the 6990, and that setup is still quieter than the 6990.
This leads us to our exceptions, and why we believe the 6990 is truly a niche product.
- Quad-CrossFire; this is going to be the highest performing AMD solution at this time, power and noise be damned. This requires a motherboard with PEG slots three slots apart (lest you choke the first 6990), but it’s achievable.
- 5x1P Eyefinity. At five-panel resolutions you’re going need a pair of powerful GPUs, but given AMD’s CrossFire Eyefinity limitations at the time only 2 cards can directly drive five monitors: the 5870 Eyefinity 6, and the 6990. Ultimately MST hubs will allow the 6970CF to do this, but for the time being the 6970CF is limited by the number of displays a single card can drive without a hub.
- If you absolutely cannot fit two cards in your computer. This is often the traditional domain of the dual-GPU card, but the 6990’s cooling and power requirements put this in jeopardy. Most micro-ATX cases would simply not be suitable due to cooling needs, meanwhile motherboards with two or more PEG slots are increasingly common. There are very few computers with a single PEG slot that could power and cool the 6990 without a complete overhaul in the first place.
Dual-GPU cards have always been a niche product, but the 6990 really takes this and runs with it. There’s no significant power/noise savings to be found by consolidating two GPUs on to a single card, and as we said earlier with the dual-exhaust cooler the 6990 is effectively two video cards on one PCB. This isn’t a bad thing – the 6990 is the world’s fastest video card after all – but it drives the card in to some very specific niches. If you fall in to these niches, then the 6990 is certainly the card for you. At 22% faster than the 5970 it isn’t a massive performance boost, but it certainly has earned its place.
But if you don't fall into these niches, then there’s nothing the Radeon HD 6990 offers you today that the 6950/6970 didn’t offer in CrossFire mode yesterday. In this case while AMD’s king card is an engineering marvel for its ability to handle so much power in a confined space, as a product on the market it won’t be quite as significant as the title implies.
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Spazweasel - Tuesday, March 8, 2011 - link
I've always viewed single-card dual-GPU cards as more of a packaging stunt than a product.They invariably are clocked a little lower than the single-GPU cards they re based upon, and short of a liquid cooling system are extremely noisy (unavoidable when you have twice as much heat that has to be dissipated by the same sized cooler as the single-GPU card). They also tend to not be a bargain price-wise; compare a dual-GPU card versus two of the single-GPU cards with the same GPU.
Personally, I would much rather have discrete GPUs and be able to cool them without the noise. I'll spend a little more for a full-sized case and a motherboard with the necessary layout (two slots between PCI-16x slots) rather than deal with the compromises of the extra-dense packaging. If someone else needs quad SLI or quad Crossfire, well, fine... to each their own. But if dual GPUs is the goal, I truly don't see any advantage of a dual-GPU card over dual single-GPU cards, and plenty of disadvantages.
Like I said... more of a stunt than a product. Cool that it exists, but less useful than advertised except for extremely narrow niches.
mino - Tuesday, March 8, 2011 - link
Even -2- years since the release of the original Crysis, “but can it run Crysis?” is still an important question, and for -3.5- years the answer was “no.”Umm, you sure bout both those time values?
:)
Nice review, BTW.
MrSpadge - Tuesday, March 8, 2011 - link
"With a 375W TDP the 6990 should consume less power than 2x200W 6950CF, but in practice the 6950CF setup consumes 21W less. Part of this comes down to the greater CPU load the 6990 can create by allowing for higher framerates, but this doesn’t completely explain the disparity."If it hasn't been mentioned before: guys, this is simple. The TDP for the HD6950 is just for the PowerTune limit. The "power draw under gaming" is specified at ~150 W, which is just what you'll find during gaming gaming tests.
Furthermore Cayman is run at lower voltage (1.10 V) and clocks and with less units on HD6950, so it's only natural for 2 of these to consume less power than a HD6990. Summing it up one would expect 1.10^2/1.12^2 * 800/830 * 22/24 = 85,2% the power consumption of a Cayman on HD6990.
MrS
mino - Tuesday, March 8, 2011 - link
You shall not hit them so hard next time. :)Numbers tend to hurt one's ego badly if properly thrown.
geok1ng - Tuesday, March 8, 2011 - link
The article points that the 6990 runs much closer to 6950CF than 6970CF.I assume that the author is talking about 2GB 6950, that can be shader unlocked, in a process much safer than flashing the card with a 6970 BIOS.
It would be interesting to see CF numbers for unlocked 6950s.
As it stands the 6990 is not a great product: it requires an expensive PSU, a big case full of fans, at price ponit higher than similar CF setups.
Considering that there are ZERO enthuasiast mobos thah wont accept CF, the 6990 becomes a very hard sell.
Even more troubling is the lack of a DL-DVI adapter in the bundle, scaring way 30" owners, precisely the group of buyers most interested in this video card.
Why should a 30" step away from a 580m or SLI 580s, if the 6990 the same expensive PSU, the same BIG case full of fans and a DL-DVI adapter costs more than teh price gap to a SLI mobo?
Thanny - Tuesday, March 8, 2011 - link
This card looks very much like the XFX 4GB 5970 card. The GPU position and cooling setup is identical.I'd be very interested to see a performance comparison with that card, which operates at 5870 clock speeds and has the same amount of graphics memory (which is not "frame buffer", for those who keep misusing that term).
JumpingJack - Wednesday, March 9, 2011 - link
:) Yep, I wished they would actually make it right.
The frame buffer is the amount of memory to store the pixel and color depth info for a renderable frame of data, whereas graphics memory (or VRAM) is the total memory available for the card which consequently holds the frame buffer, command buffer, textures, etc etc. The frame buffer is just a small portion of the VRAM set aside and is the output target for the GPU. The frame buffer size is the same for every modern video card on the planet at fixed (same) resolution. I.e. a 1900x1200 res with 32 bit color depth has a frame buffer of ~9.2 MB (1900x1200x32 / 8), if double or tripled buffered, multiply by 2 or 3.
Most every techno site misapplies the term "frame buffer", Anandtech, PCPer (big abuser), Techreport ... most everyone.
Hrel - Wednesday, March 9, 2011 - link
Anyone wanting to play at resolutions above 1080p should just buy two GTX560's for 500 bucks. Why waste the extra 200? There's no such thing as future proofing at these levels.wellortech - Wednesday, March 9, 2011 - link
If the 560s are as noisy as the 570, I think I would rather try a pair of 6950s.HangFire - Wednesday, March 9, 2011 - link
And you can't even bring yourself to mention Linux (non) support?You do realize there are high end Linux workstation users, with CAD, custom software, and OpenCL development projects that need this information?