Cooling Issues with SLI Msi GTX980ti Gaming 6g

[Ololezhka]

Top of the morning to you all. I've recently built a pc and I am having some serious issues with gpu temps. In Witcher 3 the top gpu temp reaches 90C under 85% load while the bottom stays around 55-65 with 70% load. I've reconfigured the primary card in bios to the bottom card. Connected the display output to it. Nothing of that sort helped. The case I have is Corsair Obsidian 350D. I have also changed the thermopaste on both cards.

I have 6 fans set up, 2 fans at the front of the case set to intake, 1 on the side-window set to intake. 2 at the top of the case set to exhaust with 240mm radiator, and 1 fan set at the rear of the case set to exhaust also. I disconnected the backplate from the bottom card to allow more space between the cards. Unfortunately I have a micro-ATX motherboard (Gygabyte X99M) so I cannot plug the bottom card further. I am getting very worried about the temps, hence I ask for your guys advice.

All the fans I use are from corsair. The two liquid cooling fans are the only high pressure fans in the case, the rest are high airflow. I've tried looking for a cheap liquid cooling solution that corsair has for graphics cards, unfortunately my cards are not compatible due to some weird setup I think. Unfortunately I cannot buy a liquid cooling loop for the graphics card due to the price... 120 euros for the card waterblock only. I am considering it tho. Anyway, for now I need a solution to this problem, although 90C might seem like temperature that a card might withstand, I do not want the huge performance loss associated with it. I would very much appreciate any help I could get, let that be hardware or software. I have thought about underclocking or/and fixing the top card to a certain usage limit, I would appreciate any info on that, too. For some reason the top cards gets used about 10% more in game all the time.

Here are my system specs
Case: Corsair Obsidian 350D
Motherboard: Gygabyte X99M
CPU: Intel I7 5820k OC 4.3Ghz
Ram: Corsair DDR4 8gbx2 modules 2400Mhz
Sata and M.2 ssd's
PSU: EVGA Supernova P2 850W
GPU: 2xMsi GTX980ti Gaming 6g

I would be grateful to anyone who might have some advice for me.

 

[Aeacus]

To give us an idea about how your case internals are looking, is this picture close match to your setup?
Image:

As far as i know, Corsair Obisdian 350D doesn't offer a side fan mounting location. Did you jerry-rigged the side fan onto the side panel by yourself?

Few possible solutions:

1. Use a bigger case that has better cooling options. E.g Corsair Carbide Series 500R (comes also in white color),
specs: http://www.corsair.com/en/carbide-series-500r-mid-tower-case

2. Use a blower type GPU rather than open air type GPU.
In the small cases, like yours, it's best to use blower type GPUs since they exhaust the hot air directly to the outside of the PC.
Using open air type GPU leaves the hot air circling inside the case. The smaller the case - the hotter case internals can get.

3. Do some more jerry-rigging.
First, switch the side fan from intake to exhaust.
Second, measure the space you have between the PSU and 3.5" HDD cage. Try to install bottom intake fan there. 140mm AF fan would be ideal but 120mm AF fan would also do. But to do that, you have to drill the fan mounting holes in the case bottom and also drill enough holes to form a grille from where the bottom intake fan can draw it's air. If you don't use 3.5" HDD cage then you should have more room where to install bottom intake fan. Try to mount the bottom intake fan as close to the PSU as you can.

 

[Karadjgne]

You could try changing the intake fans. The problem with many of the high cfm fans is the distribution cone of the fan exhaust. Sure they'll put out some air, it just doesn't flow, it's such a wide cone it goes everywhere. Using a directed cone, such as used by the Noctua nf-f12, puts all that air basically in a straight line, right at the gpus. Most of the issue with gpu 1 overheat is lack of cooler air, most of its draw is from the exhaust of gpu 2. Side fans as intakes aren't a good solution, they tend to just force the warm exhaust back onto the gpus, making gpu 1's intake that much easier. Use the side fan as exhaust instead, which will help draw not only gpu 2 exhaust away from gpu 1 intake, but draw the intake flow towards the gpus.

Also, change the fan curve for intake. Set the intakes at a slightly higher rpm that'll also raise the speeds at a higher rate. If necessary, use SpeedFan and set the intake address to correspond to gpu 1 temp, not the default temp address. This'll jack up intake fan speeds with gpu temps.

 

[Ololezhka]

To give us an idea about how your case internals are looking, is this picture close match to your setup?
Image:

Hey there, that is exactly how my pc looks. I have indeed drilled a few holes in the plastic side window to mount the fan. Formed a grille also. I have read your advice and came to a good understanding of how much air I need in my case. I have also read Karadjgne's advice which helped me to find the answer also.

Since the case is new I decided not to buy a new one just for the mounting space. The graphics cards unfortunately are used and I probably wont be able to sell them to get blower cards. Drilling holes at the bottom of the case might have been of a more significant help but, drilling in aluminium with a drill that hardly drilled in plastic might be an issue. What I decided to do was to mount the cpu heatsink at the front of the case with 2 high pressure fans on both sides, since corsair fans don't blow in a straight line I though that may be a good idea. Now, the 4 fans working together provide a decent straight line airflow in the case. I have changed the orientation of the side fan to exhaust also which was of huge help also. The end result was a decrease of 10C of the top card under full load, I don't know about you but 80-85 C sounds a lot more plausible that 90-95. I also mounted 2 airflow fans at the top of the case in place of cpu heatsink which I moved. I believe that I have done as much as possible since 8 fans in a microATX case sounds crazy. Anyway, I very much appreciate your help. If you have any other suggestions, please, feel free to comment again!

 

[Ololezhka]

You could try changing the intake fans. The problem with many of the high cfm fans is the distribution cone of the fan exhaust. Sure they'll put out some air, it just doesn't flow, it's such a wide cone it goes everywhere. Using a directed cone, such as used by the Noctua nf-f12, puts all that air basically in a straight line, right at the gpus. Most of the issue with gpu 1 overheat is lack of cooler air, most of its draw is from the exhaust of gpu 2. Side fans as intakes aren't a good solution, they tend to just force the warm exhaust back onto the gpus, making gpu 1's intake that much easier. Use the side fan as exhaust instead, which will help draw not only gpu 2 exhaust away from gpu 1 intake, but draw the intake flow towards the gpus.

Also, change the fan curve for intake. Set the intakes at a slightly higher rpm that'll also raise the speeds at a higher rate. If necessary, use SpeedFan and set the intake address to correspond to gpu 1 temp, not the default temp address. This'll jack up intake fan speeds with gpu temps.

Thank you for the reply, I believe to have found a solution to the problem thanks to you and Aeacus. I have explained my solution in the reply above. Thanks for the suggestion that the air from the fans does not flow in a straight line, that was partially why I found a solution. I have changed the orientation of the side-fan as well, that provided a ton of help to those temps!

 

[Ololezhka]

One more question, which fan (HF or HP) is better for side window exhaust?

 

[Karadjgne]

HF. Normally. Air is air, it's the same on both sides of the fan. If your fan has a 100cfm rating, it'll move 100 cubic feet in a minute. It's gotta draw that air from somewhere. The flip side is high pressure fans, they move slightly less air but do it more forcefully. Which is better when there are obstructions like hdd cages, needing air to actually move further etc. So normally HF is better for exhaust, but if you have a restrictive vent (smaller holes with lots of plastic between them) then HP is better.

 

[Ololezhka]

HF. Normally. Air is air, it's the same on both sides of the fan. If your fan has a 100cfm rating, it'll move 100 cubic feet in a minute. It's gotta draw that air from somewhere. The flip side is high pressure fans, they move slightly less air but do it more forcefully. Which is better when there are obstructions like hdd cages, needing air to actually move further etc. So normally HF is better for exhaust, but if you have a restrictive vent (smaller holes with lots of plastic between them) then HP is better.

I should probably change to HP then, the holes which I made aren't that frequent. What do you think about the placement of the side fan? Should I keep it in the middle or maybe move it right back to where the sli bridge is (but still covering the card). I though of moving it back since the front fans are blowing directly at the cards and the exhaust on the side probably doesn't allow that air to go through to the rear fan of the top gpu. Thanks

 

[Aeacus]

For side exhaust, i too suggest that you go for a HP (aka SP - Static Pressure) fan. Since your GPUs probably are very close to the side fan, SP fan is needed to draw the hot air out from the internals of GPU.
If there isn't any airflow restrictions near the fan, a HF (aka AF - Air Flow) fan will do better.

For side exhaust, the best fan would be Corsair ML series since it's both high on AF and SP,
link: http://www.corsair.com/en/cooling/ml-series-fans

Edit:
I'd move the side exhaust fan towards the rear of the case, near SLI bridge to get better airflow inside the case.

 

[Karadjgne]

Yep, use that exhaust. Fans don't work by pushing air to create a vacuum in front, it's the opposite. Spinning blades create a vacuum by removing adjacent air, what you get out back is the exhaust. So moving that fan away from the center of the gpu will put the gpu exhaust closer to between a vacuum and a supply of fresh air. Basically it'll help draw the air past the gpu. That's the theory anyways. Testing may prove or disprove it.

 

[Ololezhka]

For side exhaust, i too suggest that you go for a HP (aka SP - Static Pressure) fan. Since your GPUs probably are very close to the side fan, SP fan is needed to draw the hot air out from the internals of GPU.
If there isn't any airflow restrictions near the fan, a HF (aka AF - Air Flow) fan will do better.

For side exhaust, the best fan would be Corsair ML series since it's both high on AF and SP,
link: http://www.corsair.com/en/cooling/ml-series-fans

Edit:
I'd move the side exhaust fan towards the rear of the case, near SLI bridge to get better airflow inside the case.

So, I followed on your suggestion to move the fan towards the back of the case. Unfortunately the side panel could not stand any more holes being drilled and broke, nevertheless I broke it even more and fortunately the hole is perfect for the new fan. I bought a 140mm Noctua NF-A14 and damn its loud! I've created a fan profile with corsair link since the fan is connected to the pump. The result was pretty good, the maximum temperature of the top gpu is 86C under 100% load in heavenbench. Unfortunately I've realised that the 140mm fan creates so much negative pressure in the case that the other exhaust fans aren't doing anything. I removed the top 2 120mm fans and left the rear fan on.

I continue to think about how I can improve the cooling even more, since I'm not going to buy a full liquid loop. I though maybe if I change the orientation of the side fan to intake and the front 4 hp fans to exhaust I could achieve a better result. If I were to do that I would also add the exhaust fans at the top. What do you think about this idea and what is your opinion on the new fan?

 

[Ololezhka]

Yep, use that exhaust. Fans don't work by pushing air to create a vacuum in front, it's the opposite. Spinning blades create a vacuum by removing adjacent air, what you get out back is the exhaust. So moving that fan away from the center of the gpu will put the gpu exhaust closer to between a vacuum and a supply of fresh air. Basically it'll help draw the air past the gpu. That's the theory anyways. Testing may prove or disprove it.

Please read the top reply, it is to the both of you.

 

[Ololezhka]

Another update. I have just tried changing the orientation of the side fan and mounted the 2 exhaust back at the top. After 10mins of heaven the temperature of the top gpu reached a maximum of 82C and the bottom gpu was at 60C. The noctua fan can spin up to 3000rpm. These temps were reached with the fan spinning at 2200. Increasing the speed did not really have an instant impact and the noise level was pretty extreme. I believe that by having more exhausts I can indeed decrease the temperature even further. Although the airflow in the case is all over the place I believe to have achieved a significant decrease of 10C from 94C when corsair fan was in place.

 

[Aeacus]

For your small case, Negative Pressure is better than Positive Pressure.

An article to read: http://www.tomshardware.co.uk/faq/id-1858957/airflow-101-setting-fans-keeping-computer-cool.html
Also, a more in-depth article as well: http://www.tomshardware.com/reviews/cooling-air-pressure-heatsink,3058.html