Date:
Tuesday , February 17, 2009
Author:
Brent Justice
Editor:
Kyle Bennett
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NVIDIA GeForce GTX 295 Quad SLI

We take a close look at gameplay performance with the GeForce GTX 295 Quad SLI and compare it to Radeon HD 4870 X2 CrossFireX. The results may surprise you and make you question whether Quad SLI or CrossFireX are worth investing in for gaming at this time. You will want to see what happened with GTA4.

Introduction

This past January the GeForce GTX 295 from NVIDIA was launched. We evaluated a single BFGTech GeForce GTX 295. Our impressions were that it was indeed a fast video card that allows a high level of gameplay experience on large displays, but the high price coupled with AMD’s price drops on the Radeon HD 4870 X2 meant it had some tough mountains to climb. Its saving grace, which may push it over the edge into “Must Have Hardware” is its ability to run in a Quad SLI configuration. We are here today to see if Quad SLI is necessary with today’s games, and if it is something worth pouring your money into. Our conclusions may surprise you.

Going back to our initial evaluation we can see what the GeForce GTX 295 is all about. What we are looking at are two GPUs on two separate Printed Circuit Boards (PCBs) connected via an SLI interface in a “single” package format. This differs from AMD’s implantation of dual-GPUs on the Radeon HD 4870 X2. The Radeon HD 4870 X2 has both GPUs on one single PCB with integrated controller hardware to hardware CrossFire configuration on that one PCB. Whether which method actually results in improved gameplay and performance is debatable. The fact of the matter is that with both implementations memory is still not shared or pooled between the GPUs.

Each GPU has to reach into its own framebuffer connected around each GPU. This means that on the Radeon HD 4870 X2 there is only 1GB of actual memory available to each GPU as the data has to be replicated between all GPUs memory banks. The same goes for the GeForce GTX 295, there is 896MB of memory available to each GPU and they have to replicate data, no sharing or pooling supported. So when you start putting four of these GPUs together, in Quad SLI you become increasingly memory bandwidth and capacity limited. The shader power of four GPUs is there, but the memory doesn’t increase with that shader power, it stays constant. This means it could lead to severe memory bottlenecking, on both CrossFireX and Quad SLI. This evaluation will show that bottlenecking taking place in games and make you question whether CrossFireX or Quad SLI is a proper investment right now. In fact, you will want to pay special attention to the Grand Theft Auto IV gameplay page.

GeForce GTX 295 Quad SLI

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Setting up Quad SLI is a breeze. In the past we have had issues with Quad SLI, especially when it was very first introduced. All the problems we had with Quad SLI in the past no longer exists. This shows very good progress on hardware and software support for SLI in general. We always start with a clean OS and have no video drivers loaded, so the first thing was to simply plug each video card into the appropriate PCIe slot on our 790i motherboard. Then we proceeded to plug in all power connectors.

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Note you will need two 8-pin and two 6-pin to make this configuration work. On SLI Zone you will find Quad SLI certified PSUs to use with two GeForce GTX 295 video cards. Their list right now isn’t that long for officially supported PSUs. Of course given enough amps and wattage, any PSU should suffice, just don’t undercut yourself here, a good PSU will make or break your system, and when configuring something like Quad SLI you are going to want something beefy.

After connecting all appropriate hardware connections, including the single SLI bridge that is required, we booted the system. We then installed the latest drivers at the time of this evaluation which was 181.22. Driver installation went smoothly, we rebooted and a pop up box came up telling us we could improve performance by enabling SLI. You see, with one GeForce GTX 295 you do not need to enable SLI because it is enabled by default. However, when you install two video cards to enable Quad SLI you do have to manually turn it on in the driver control panel. We did this, screen flashed a few times, and we were back to the desktop with SLI enabled and all our icons all over the place as usual. We went ahead and gave it a reboot anyway, as we like to just to make sure everything is really enabled. Once everything came back up we jumped in our games and Quad SLI was working with no problems.