Installation:

The Corsair Nautilus GPU Blocks are compatible with 7xxx Series video cards and single only with the 7950GT. As with many a 7900  Removing the stock heat sink reveals that the stock heat sink isn't well centered over the GPU. And unless you've seen what's under your stock heat sink, the chances are that your own graphics card heat sink doesn't make good contact with the memory nor is it centered over the GPU.

Stock Heat Sink

Plastic Removed

Reading Through

This common issue can be the sole cause and reason for high GPU temperatures. It's bad enough when the heat sinks are made with unpolished bases and cheap thermal pads, but poorly placing the heat sink and can barely do the job. A few more dollars in machining and better thermal tape can do wonders for temperatures and eliminate the need for that unnecessarily loud fan. Why some companies don't consider the benefits over another few dollars is often beyond reason.

Diagram

Mounting Kit

Tightening Screws

The Nautilus uses a pretty simple process of washers, tension springs, and standoff screws to fasten the block securely. The block is best installed lying on a flat surface. You first have to screw in the standoffs and set the appropriate washers. The directions are quite clear on how this is done. After cleaning off and applying fresh thermal paste on the GPU and Memory, the graphics card was centered over the stand offs. This is the point as with any other VGA block where you should take your time and use a bit more caution as you push the video card on to the block. After pressing little by little till the block was seated flat and even, the screws and washers were added. These were tightened with the same exact caution. Each screw should be tightened down a little at each time so that the block makes the best contact slowly otherwise you risk damaging your GPU. Once the screws are all sufficiently tightened, the graphics card and block become one solid mass.

Back Plate Finished

As you can see from the pictures, the once meager 7900 GT looks more like a very substantial and capable graphics card. The block makes perfect contact with all of the memory modules and GPU which is what will really decide how the Nautilus will perform. All of this extra copper also adds quite a bit of weight to the graphics card which means a little more care should be taken when installing. However, the weight isn't enough to stress the PCB or make the card feel like anything less. The graphics card basically now feels like one solid component without any wiggling or movement from the Nautilus making it feel more like a quality upgrade.

Top	Bottom	Back
Test Installation	Checking for Stability	Connected

For SLI operations, the process is simply repeated on the second graphics card. Both video cards can be installed in the motherboard if you have it removed to help keep them standing, or you can attach the SLI Bridge Channel to one card. Using something to hold the video cards up is the quickest method, otherwise you can just take your time as you add the screws connecting the next card. Essentially, the barbs should be facing away from the PCI bracket when it's finished. It doesn't matter which one you use for the in or out directional flow.

Assembly	One Connected	Tight Seal
Aligning 2nd Block	Tightening	Finished

In this test system, the Koolance EHX-1050 and Swiftech Apogee GT were used since they can dissipate a great amount of heat. It may be necessary to upgrade your single fan radiator if it isn't capable of handling around 600 watts of heat dissipation. SLI systems can kick up a lot of heat especially when coupled with a CPU and chipset water block.

This test is a good excuse to get some more Battlefield 2 and Battlefield 2142 games in to check average temperatures. Game demos were played off and on in between actual gaming while watching the temperatures rise and fall. The GPU gets very warm after about 30 minutes of high detailed, hardcore games on its stock heat sink and fan.

Chopper Deck With Shield

Titan Being Attacked

At idle the water block kept the GPU very, very cool. This is the lowest idle GPU temperature this 7900 GT has ever seen. This is especially note worthy since the Corsair Nautilus completely covers the video memory as well as a hot GPU. The heat from the memory isn't very much, however. And the only time the memory really starts to heat up is when the graphics card is under full load.

Corsair 7900 GT Nautilus

After a good couple hours of solid graphics intensive benchmarking, the temperature increased by a couple degrees. The nice thing about the Nautilus during all the benchmarking is the absolute silence. The stock GPU heat sink can get a bit loud under load, especially with the loaded stock video BIOS. Sometimes you can find a modified or patch BIOS from the manufacturer, but it won't get rid of the noisy fan under full load.

Water Cooling System @ Medium

Maximum OC Under Load

Since the temperatures had increased only just a bit, it was time to see if raising the GPU and video memory frequencies would have a drastic effect. The GPU and memory were overclocked to check for any noticeable performance gains as well as to see if any new clock barriers could be broken due to the extra cooling. The video graphics card's GPU core frequency reached 580GHz and the memory frequency maxed out at 1.69MHz before any artifacts or issues developed. This seems to be the video card's maximum overclock even though the temperatures remained so very low.

After another couple hours of video crunching, the stock cooled 7900 GT would not run the same overclocked Core and Memory frequencies even close to the Nautilus 7900 GT simply because the card became too hot. And the overclock wouldn't remain stable past 30 minutes worth of crunching. However, with the Nautilus installed, the maximum overclock was stable and so very much cooler.

Ambient Temps @ 21 C

Basically, the temperature results say it all in the best possible way. The temperatures are so much lower than the stock heat sink and past VGA water block tests, that I had to double check the results with a temperature sensor which reported temps within 1 degree. Even with the Nautilus'  covering both the GPU and each memory module, the temperatures remained well below the stock cooler. One would think that this is wouldn't be the case, especially when the memory can heat up under load and especially over clocked.

Stock vs. Overclock Performance

After all the beatings and torture testing, the 7900 GT still performs like a brand new card. I typically don't operate my graphics cards above specs since most video games are still playable at high resolutions without overclocking. Sometimes certain video games cause the frame rates to drop a little lower than usual due to intense game scenery. When maximum resolutions are applied, it usually pays off when overclocking the card. The biggest benefits I would have to say the Nautilus offers are extra performance possibilities, and much, much less heat and noise that come with stock heat sinks.

Did I already mention how very quiet my system is now? I can barely hear the very low hum of the pump if I put my ear up to the computer case. Water cooling can literally be so very cool and nice to have inside your system. And there is usually hidden potential in your graphics card that only something like water cooling can allow you to tap in to. If your graphics card is one of the already insanely factory clocked versions, then water cooling can actually allow you to pull a little more overclock and keep it stable since the heat is the common prohibiting factor.


Conclusion:

Performance graphics cards operate under some extreme frequencies resulting in serious heat and performance issues, especially in warmer climates. Noise is also an ever present problem as the stock cooler fans spin at their maximum to try and keep up with task at hand. Extreme users and audiophiles alike often enjoy their games and programs running under the best and most silent conditions. Water cooling will continue to be the best way to eliminate extreme heat and noise.

The Corsair Nautilus SLI-VGA Water Blocks can control those temperatures and eliminate that incessant loud cooling fan. With thermal issues still lurking around every performance card release, over clocking is becoming less and less successful. The Nautilus helped achieve and maintain the test video card's highest most stable overclock by keeping the GPU and video memory down to a 46 C temperature without any noise. Performance like this is synonymous with Corsair. If you find yourself requiring this particular change of pace, then the Corsair Nautilus SLI-VGA Water Blocks is a very easy choice.