It's been a while since I visited SPCR, good to see it's still up and running. Over time I thought all was good in silent pc land seeing how more and more manufacturers were putting a lot of effort to make their products quiet, which is why I haven't visited SPCR in a couple of years now... Alas, my fantasies have been shattered after I bought dual fan xfx 7950
. As most dir hard SPCR'ers know it's hard to trust anybody else who says it's quiet just because most everybody else doesn't have as high standards when it comes to noise. So I went with dual fan design since it seemed like my best bet. It is quiet in idle. It uses two 80mm or so'ish fans that spin at around 1000rpm at idle (20% speed) making the card inaudible at idle. However, the fans quickly ramp up with any kind of load, playing l4d, a relatively old game by now, resulted in a very very loud fan noise. Something had to be done.
At first I tried to silence the card by taking the shroud and both fans off, exposing full card length heatsink and strapping two 120mm 800rpm slipstream fans, which seemed like a perfect fit but that attempt has failed because the card overheated way too quickly. Even downclocked down to 400Mhz core from default 800Mhz, it still hit 101 celsius playing l4d.
I started looking for alternative solutions, I found a few, in the 80$ range which was ridiculously expensive. So I turned my attention to old trusty Accelero S1 design in the new "Plus" reincarnation. I couldn't find any information on the difference between S1v2 and S1Plus on the web, so I thought Accelero beefed up the heatsink a little, but sadly I was proven wrong, physically, the S1Plus is about the same size as S1v2 with only minor differences in heatpipe locations. Officially S1 Plus doesn't list 7950 as compatible, and the bad news is it's not... not unless you mod it. I apologize for no pictures, but it's really not that difficult to understand the issue. The problem with 79xx is that they come with protective shim around the actual GPU die as can be seen here in ATOT review
. The actual GPU die is slightly recessed relative to the protective shim, so if you simply slapped S1 Plus on the card, it would rest on the protective shim and not make an actual contact with the GPU die - there is about 1-1.5mm gap between the two. The XFX heatsink actually has a slight bump in the middle to make sure it makes full contact with the GPU die. Nvidia cards come with full "lid" over GPU so you don't have that problem, however that is not the case with 79xx. Which leaves you with 3 choices:
1. Remove the protective shim - very risky and voids warranty for sure.
2. Slap a 1-2mm sheet of metal on the 79xx GPU die and then slap S1 Plus on top of it - can be difficult and you would be reducing efficiency.
3. Shave off extra metal from S1 Plus base plate that would otherwise come into contact with 79xx protective shim.
In my case, I was short on time and I already had a dremel, so my choice was clear. I decided to shape S1 Plus to make the contact with GPU die. I carefully marked the areas that would need to be shaved off with razor blade, put on my protective glasses, and started chipping away with dremel at the heatsink. All in all it took me about 15-25 minutes, mostly because it was my first (and only) time doing it, so it involved some trial and error. But in the end it was worth it. I put some AS5 on the die, pressed heatsink to it to make sure it made full contact, which it did, and put the screws in.
The end result is beautiful. I used the same two 120mm 800RPM slip stream fans.
At idle I keep the fans at around 7V making them essentially inaudible, with two monitors connected the card idles at around 41-45 degrees. That's a 10 degree drop compared to stock heatsink. Keep in mind that I run two monitors from the same card so my idle power draw and the temperatures are higher than what you may see on the web elsewhere because most people only run a single monitor.
At load I run the fans at 12V to stay on the safe side, it is a little loud for me, but still acceptable, they are 800rpm fans after all. With card overclocked to 975Mhz core, full 100% GPU load, ambient temperature of 18 degrees celsius, and fans at 800rpm the full load this morning was 61 degrees celsius. The temperature may drop a bit after AS5 settles in, but even if it doesn't 61 degrees at load is about 20 degrees lower than stock heatsink and way quieter too.
So, in the end, getting S1 Plus to fit 79xx requires some work, but it is relatively easy if you have the right tools. I still cannot believe just how crappy stock heatsink is, and I'm still amazed at how 5 year old S1 design still manages to keep the latest video cards cool and quiet, and at only $30 shipped too!EDIT
So my video card temps started to rise to the point where under heavy load I was getting artifacts and crashing. Not sure what happened, I figure either one of the fans died (I reused one of the slipstream fans, and I think it was making brushing noise), or it got caught on something, or the S1 Plus heatsink slid or something. So I took the chance to take the card out, dremel out some more metal because I wasn't sure if the heatsink was making full contact, reapply AS5, and take some pics.
Here are the pics. The first one is showing why Accelero S1 Plus is not compatible with 7950 straight out of the box. I put some paper to the shim, as you can see, there is a gap between paper and the GPU core because it's recessed compared tot he protective shim. The second photo shows how I dremeled out the heatsink to make it fit. It's a crappy job, but it works.
Photo showing the recessed core
Accelero S1 Plus cut to fit, it might not be pretty, but it's functional
In the process I also swapped slipstreams for 800RPM s-flex'es, the ones with Sony FDB bearings, and the results are very pleasing. The temps didn't really go up, but the noise did go down a lot. I can run them full speed at 800RPM and the noise is still very unobtrusive. So life is good again