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Introduction - Quad-GPU Performance Review NVIDIA vs. AMD | [H]ard|OCP
Introduction
Wanting to achieve the best gameplay experience possible is a worthy goal for hardware enthusiasts that play video games. Enthusiasts try to obtain this by taking what they have and pushing the hardware to its limits in order to squeeze out every bit of performance the hardware is capable of. For gamers on a budget, or those looking for the best value, or bang for the buck, these type of tweaks provide performance improvements resulting in a better gaming experience for "free."
What if money wasn't a concern? What if you wanted to plop down all the cash that is required to own the best possible performing video card configuration for gaming with no tweaking? There would only be two options right now that would give you the best possible performance, and that is a Quad-GPU configuration from NVIDIA or AMD. While most gamers enjoy performance with one GPU, sometimes it just isn't enough. NVIDIA's and AMD's solution to this problem is to throw more GPUs at you and hope it does what you need.
GeForce GTX 590 SLI
From NVIDIA, you can enjoy dual-GPU on a card from the new GeForce GTX 590. The GeForce GTX 590 utilizes two GTX 580 ASICs (i.e. the actual GPU of a GTX 580 x2), however, the clock speeds are severally reduced as well as the memory speed. This reduction in frequencies has resulted in subpar performance in our evaluation. We found that the GeForce GTX 590 seemed to perform about the same as GeForce GTX 570 SLI. This wasn't entirely exciting considering the high price of $699 MSRP. However, there may be some redemption in the GeForce GTX 590 because it supports Quad-SLI. That is, you can put two GeForce GTX 590 cards in your system and connect those via an SLI bridge for Quad-SLI, or as we will call it, GeForce GTX 590 SLI (two cards with SLI enabled that contains 4 GPUs total.)
The one concern we have is that each GPU only has 1.5GB of RAM to work with. The memory is not shared in SLI using Alternate Frame Rendering (AFR), and therefore each GPU needs its own framebuffer space, and each only has access to 1.5GB. This has the potential to severely limit the performance of GTX 590 SLI, but we will see.
We are using two ASUS branded GeForce GTX 590 video cards provided to us by ASUS specifically so that we could provide this performance evaluation to our readers.
One thing we will say about the GeForce GTX 590 is that it is one sexy video card, if a video card can be sexy. NVIDIA knows how to design visually pleasing hardware. These video cards are slender and fit nicely in our motherboard with room to breathe. Both require 8-pin power connectors, and our power supply only has three so we had to use an 8-pin adapter that gets its power from two 6-pin connectors. Having enough or the right power connections is something to keep in mind if you are considering building Quad-SLI.
Configuring the display panels was a bit tricky using three DVI connections. You have to plug the displays in a certain way in order for NV Surround to work with Quad-SLI. The pattern we have above is what works, you have the right and center display on the top two ports on the primary video card, and the left display on the top port closest to the other video card. Any other configuration did not work, this is how it must be attached, at least in our experience. We have to say this is more complicated than configuring AMD Eyefinity which doesn't care where you plug in the displays. After we plugged everything in properly, the software enabled NV Surround and we were up and running with Quad-SLI enabled.
AMD Radeon HD 6990
On the AMD side, AMD has produced the AMD Radeon HD 6990 video card. This is also a dual-GPU video card, sporting two Radeon HD 6970 GPUs. These GPUs are also reduced in speed from a Radeon HD 6970 GPU, but not as severely as the GTX 590's GPUs are. The Radeon HD 6970 runs at 880MHz, and the GPUs on the Radeon HD 6990 run at 830MHz, a decrease of only 50MHz, versus the large decrease of 165MHz with the GTX 590 vs. GTX 580 GPU. The memory is also not as severely decreased in speed as the GTX 590 is compared to the GTX 580.
This means that each Radeon HD 6990 GPU is closer in performance to its native ASIC performance than the GTX 590 is. Also, AMD provides a BIOS switch atop the video card that lets you easily put the 6990 into full 6970 GPU clock speeds should you wish to overclock the card.
AMD supports Quad-GPU by allowing us to plug in two Radeon HD 6990 video cards and connect those via a CrossFireX link bridge. The Radeon HD 6990 has 2GB of RAM per GPU, 500MB more per GPU than the Quad-SLI configuration. This means that each GPU has more RAM to access in the same Alternate Frame Rendering (AFR) method used in multi-GPU configurations today. This higher memory capacity should theoretically allow us to utilize the performance better and enable higher settings at high resolutions.
Setting up Radeon HD 6990 CrossFireX was similar to GTX 590 SLI, we installed both video cards, setup the bridge connector and plugged in the power similarly. When it came to the display setup configuration it was much easier than Quad-SLI. It didn't matter what order we plugged the display port connectors in on the primary card, the software did the job of configuring everything. Also a difference is that all three displays can be plugged into the primary display with AMD Eyefinity, whereas with NV Surround you have to plug two displays in the primary card and one display in the secondary card. Personally, I like the setup of AMD Eyefinity better, its easier and quicker to get setup and going with no hassle.
Game Issues
The gameplay evaluation you are going to see today is as simple as it gets, a true 4-GPU vs. 4-GPU showoff to see who delivers the best performance and best gameplay experience and ultimately the best value.
While the setup is simple, our experiences were a mixed bag. We actually encountered a lot of game issues along the way. We've been trying to work through these issues in our testing time, and worked with NVIDIA and AMD to try and resolve these. We have even switched drivers mid-evaluation, to make sure we were up to date with the latest possible fixes. We tried to keep it as simple as we can and we will explain on each game page what we experienced. Quad GPU gameplay does not come without it problems and surely this will make you question the value of either of these solutions.
The three games we had troubles with were F1 2010, Battlefield: Bad Company 2 and Dragon Age II. It wasn't just NVIDIA or AMD that had issues either, both shared some issue with Quad-GPU. While we have tried to test as high as possible at 5760x1200 in a triple-display configuration, some games we had to actually compare at 2560x1600 on a 30" single display because of issues.
Therefore, this evaluation is a mix of testing at triple-display and single-display. We also have apples-to-apples at both resolutions in a lot of the games. We have therefore provided performance in two areas we know gamers want to see, multi-display performance and single-display performance with really fast video cards.
Test Setup:
Results:
Quick Performance Summary: HD6990 destroyed the GTX590 in highest resolutions. If you own GTX590's or HD6990's you should play on higher resolutions, if not your just wasting money. Stick to GTX 570's if you won't even go above 1920 Resolution.
Full Conclusion:
Performance Summary
The biggest surprise to us are the game issues we encountered. In three of our five games, we had an issue with something. Normally we don't have this many issues with multi-GPU solutions when looking at dual or triple-GPU performance. In our recent Tri-Fire revisit, our only issue was with F1 2010 performance. It seems that Quad-GPUs have added a layer of complexity that requires software tweaking in some games. Throw into that new technologies like NV Surround and AMD Eyefinity and there are many variables when trying to make Quad-GPUs work together. We do however feel that these issues are all software related, and something as easy as a driver or application profile fix will do the job. It does remain a fact though, moving to Quad-GPU may be a gamble in some games. This points out that there is simply not enough testing done with these "halo" configurations.
So if you play that bet, what will Quad-GPUs really get you? We have to say that all depends on which solution you go with. It is clear from all of our testing that GeForce GTX 590 SLI is being held back and limited by its memory capacity as each GPU has access to 1.5GB of RAM. This limitation has rendered the GTX 590 SLI solution limited by its capacity. In every game we played, there was some limitation we were bound by and not able to use higher gameplay settings that we knew GTX 590 SLI had the performance to muster should it not be bound by the lacking memory.
On the other hand, AMD Radeon HD 6990 CrossFireX had that little bit of extra RAM, 500MB more per GPU for 2GB total per GPU. This was just enough to allow us to use those higher settings that the HD 6990 CrossFireX clearly had the performance to push. We were able to turn on 4X MSAA at 5760x1200 in Metro 2033, we were able to have the highest settings possible enabled in this game at 2560x1200 with Depth of Field and 4X MSAA enabled, which is a first. We were able to play Crysis: Warhead at 5760x1200 with all Enthusiast settings plus 2X AA. We were able to run at 8X MSAA in Dragon Age II at 2560x1600 with the highest in-game settings. Overall, Radeon HD 6990 CFX had the performance, and it had the capacity to use it. AMD was very forward thinking when they launched this series with 2GB of RAM.
But what about 3GB GeForce GTX 580's Mr. Justice? Yes, we have heard the feedback from our valued readers on this. We are aware of 3GB GeForce GTX 580 video cards. I will state that this particular evaluation was a look at how Quad-GPU compares using the fastest dual-GPU cards from NVIDIA and AMD. The GeForce GTX 590 is currently NVIDIA's fastest dual-GPU video card that allows us to easily setup Quad-GPU. Conversely, AMD's answer is the Radeon HD 6990 dual-GPU video card which also allows Quad-GPU performance. This evaluation was a head on look at four GPUs vs. four GPUs.
We will be re-visiting Tri-Fire again using three Radeon HD 6970 video cards, and we are looking into evaluating 2-way or 3-way 3GB GeForce GTX 580 with that. These video cards are both hard to find, and expensive, which is always a concern, but we know you guys want to see it, and quite frankly we are curious too.
Value
The question here is which configuration is going to provide the best gaming value. Both are not inexpensive by any means, though Radeon HD 6990 CrossFireX can be had a bit more easily than GTX 590 SLI currently. One problem we have found currently on both ends is availability, to be honest it is harder to find GTX 590's than it is to find Radeon HD 6990's. However, there are indeed many places out of stock on 6990's as well.
Here is a Sapphire Radeon HD 6990 for $699 and currently in stock. This is about the best price we've seen so far on Radeon HD 6990's, most have been marked up to around $730 or more. That means two for Quad-GPU will cost you $1400 in total. On the other side of the fence is the exact cards we used today, the ASUS GeForce GTX 590 also for $699 which is an excellent price. Problem is, per usual for GTX 590's, it is out of stock. This EVGA GTX 590 is in stock, but it is a whopping $790 which means two will cost you $1580.
The Bottom Line
Based on our evaluations here, the Radeon HD 6990 CrossFireX solution is looking like the more value oriented setup compared to GeForce GTX 590 SLI. There are many good things going for CrossFireX Quad, you have more RAM per GPU which translates into real-world gameplay improvements, the power consumption is a bit lower, availability is a bit better, and pricing isn't as harsh. We also like the ease and simple nature of AMD Eyefinity setup. When you add all of this up, Radeon HD 6990 CrossFireX is a better value.
The way things are, GeForce GTX 590 is better suited for lower resolutions, which is odd to say, but true according to our testing. When the video card is not memory bottlenecked at lower resolutions, GTX 590 SLI performs very well, though 6990 CFX is a slight step ahead each time, it is still competitive at lower resolutions. But if you want to go for that high resolution display setup, only the Radeon HD 6990 CrossFireX will provide that Quad-GPU experience you are looking for.
Still, expect issues when it comes to gaming as neither AMD nor NVIDIA have done the proper real world testing to support these configurations the way these should be supported. And the resonating fact of the matter is that 4-GPU SLI or CrossFireX scaling always seems to fall a bit flat. We would suggest that most of our readers would be best off with a 3-GPU configuration at the most and 2-GPU solutions show the best performance scaling.
Quad-GPU Performance Review NVIDIA vs. AMD (590 SLI v 6990 CF) *56k warning*
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