Intel i9 or Ryzen?

[sean_brown]

Hi Muhammed_Hamed , May I ask, since we have similar hardware, how you are cooling your dual 3090 GPUs on your Dark Hero board? I am using the Dark Hero as well and the stock GPU coolers and it seems the first GPU is choking as its running 20c hotter than GPU 2 since they are so close to each other. Do you have the same issue and would you have any suggestions?
Thanks

[Alex_M]

Why would you put 2 RTX 3090 in such a small cramped case? No wonder they are choking. They are practically touching and both have their fans completely blocked! If you want to run 2 air cooled 3090s, you would need a motherboard that allows for at least 1 slot spacing between the GPUs and a big case with at least 3 intake and 2 exhaust fans. Maybe even undervolt the GPUs as well. An air cooled 3090 is not a GPU for a small form factor build, let alone 2 RTX 3090s. We are talking about 700W of heat in a tiny space dumping their heat on each other. If you want to run 2 RTX 3090 in the same case, I would probably look into water cooling them. You will first need to make sure your case has the capability to accommodate the radiators and reservoir/pump needed to water cool them, of course.

[sean_brown]

Why would you put 2 RTX 3090 in such a small cramped case? No wonder they are choking. They are practically touching and both have their fans completely blocked! If you want to run 2 air cooled 3090s, you would need a motherboard that allows for at least 1 slot spacing between the GPUs and a big case with at least 3 intake and 2 exhaust fans. Maybe even undervolt the GPUs as well. An air cooled 3090 is not a GPU for a small form factor build, let alone 2 RTX 3090s. We are talking about 700W of heat in a tiny space dumping their heat on each other. If you want to run 2 RTX 3090 in the same case, I would probably look into water cooling them. You will first need to make sure your case has the capability to accommodate the radiators and reservoir/pump needed to water cool them, of course.

Its not the case that sandwiching them together and causing the biggest problem. Its the mobo. But Muhammed_Hamed has the same mobo so thats why i was asking what his solution was.

this is not the final build. I am still figuring out how to setup 2 GPU properly. I am also not sure if dual GPU is the way to go as my render times are slower for some reason. Benchmark is fine, but my scene in Maya is slower when both are selected.

[Alex_M]

Slower rendering times with 2 GPUs is definitely not normal. You should send your scene to the support team at Chaos.

[Muhammed_Hamed]

Sorry about the delay, will answer both of your threads today

[sean_brown]

Sorry about the delay, will answer both of your threads today

Great, Thanks Muhammed_Hamed , I'm looking forward to your reply.

[sean_brown]

Muhammed_Hamed Hi, would you have a moment to share how you were able to prevent overheating with two 3090s sandwiched on a dark hero board? My second exchange window is closing soon so if I need to change cards, now would be the only time. My current card is the Evga ftw3 and it’s a 2.7 slot so leaves very little room between the cards. I thought about a XC3 which is a 2.2 slot but since the cooler is smaller I hear they run hot already. Are you running two MSI Supreme 3090s with stock coolers? Because those are 2.9 slot so that would leave almost no room In between cards so any input you can share on how you’ve set it up would be really really helpful.

Thanks

[Muhammed_Hamed]

My current card is the Evga ftw3 and it’s a 2.7 slot so leaves very little room between the cards. I thought about a XC3 which is a 2.2 slot the since the cooler is smaller I hear they run hot already

EVGA FTW3 is miles better than XC3, it is not just about the smaller cooler. The PCB is different, the power limit is different. FTW 3 requires 3x 8 pins while XC3 requires 2x 2 pins
Don't return your cards

would you have a moment to share how you were able to prevent overheating with two 3090s sandwiched on a dark hero board?

>> Having multiple GPUs, the bigger task is getting the hot air out of your case. I'm using an ROG Helios case, you will find that it has the best GPU thermals in any case reviews. This comes down to how massive the case is, and the fact that it is equipped with 3x 140 mm fans at the front. I replaced those stock fans with Noctua 140 mm fans. A big case will be helpful like the ROG Helios

>> Another point is how an Air cooler is not helpful with 2 GPUs, because again the biggest factor here is getting rid of the hot air. Using an AIO with exhaust fans(preferably at the top of the case) will be helpful. This way you don't deal with any hot air inside the case from the air cooler, this affects the performance of your Air cooler as well. Right now you have the backplate of the card nearly touching the heatsink of your CPU Cooler, this backplate is burning to the touch and will project hot air into the air cooler fans. I won't be surprised if your CPU thermal throttles when you do GPU rendering(which could affect performance as well)
An air cooler is fine with one GPU, but with 2 GPUs consuming over 800 Watts you get a lot of heat inside the case. I could have advised against an Air cooler earlier, didn't know you would go for 2 GPUs

>> The third point is that undervolting could help a lot, those cards use aggressive voltages out of box. Watch my video on the process, it will lower your temps by 10 to 15 degrees and this here is the easiest solution I think

>> For me personally I have one GPU in the first slot and the other GPU in the 3rd slot on the board, so there is a lot of spacing between them. I have my 2x 3090s SuprimXs heavily overclocked, they run at 65 degrees C at max
If you need NVlink you will not be able to use this configuration, you will need to use the first and second PCIe slots. Another note that the third PCIe slot uses x4 bandwidth Gen 4 shared with other devices, so you shouldn't install a second NVMe on your board.. but overall you don't lose any performance on PCIe Gen 4 x4, I have tested this extensively
You probably need a big case for this configuration
My setup is Here and here

>> There are more solutions with rise cables and an external GPU rack, or watercooling over which the cards become single-slot. I can give details over these if you want, let me know

The advice here is personal, this applies to everything I wrote in this thread.. undervolting is safe and all, you can never damage your hardware using AfterBurner, still the point is cannot give this kind of advice as a Chaos employee, proceed at your own risk.

Best,
Muhammed

[Muhammed_Hamed]

ards will not fix it. I did look at the settings for MS Teams and it actually has an option to enable or disable GPU hardware acceleration. Very interesting. I hope it gets resolved.

are you able to tell if this bug affects vray when rendering in Maya or is it only the benchmark app?

We have provided everything we have to Nvidia about this issue, I hope there will be a solution soon.

Anything that applies to the Benchmark applies to V-Ray in Maya

[Muhammed_Hamed]

I am also not sure if dual GPU is the way to go as my render times are slower for some reason. Benchmark is fine, but my scene in Maya is slower when both are selected.

You need a scene that take +5 minutes to render for proper performance scaling, 20 seconds renders will have random results, one of the GPUs probably didn't get a chance to engage in rendering . Another point is that V-Ray GPU will move the scene to GPU memory, which takes from seconds to one or 2 minute for complex scenes, this will not be any faster if you add more GPUs. So longer renders will always be more accurate, as scene compilation will be short compared to rendering itself

[sean_brown]

EVGA FTW3 is miles better than XC3, it is not just about the smaller cooler. The PCB is different, the power limit is different. FTW 3 requires 3x 8 pins while XC3 requires 2x 2 pins
Don't return your cards



>> Having multiple GPUs, the bigger task is getting the hot air out of your case. I'm using an ROG Helios case, you will find that it has the best GPU thermals in any case reviews. This comes down to how massive the case is, and the fact that it is equipped with 3x 140 mm fans at the front. I replaced those stock fans with Noctua 140 mm fans. A big case will be helpful like the ROG Helios

>> Another point is how an Air cooler is not helpful with 2 GPUs, because again the biggest factor here is getting rid of the hot air. Using an AIO with exhaust fans(preferably at the top of the case) will be helpful. This way you don't deal with any hot air inside the case from the air cooler, this affects the performance of your Air cooler as well. Right now you have the backplate of the card nearly touching the heatsink of your CPU Cooler, this backplate is burning to the touch and will project hot air into the air cooler fans. I won't be surprised if your CPU thermal throttles when you do GPU rendering(which could affect performance as well)
An air cooler is fine with one GPU, but with 2 GPUs consuming over 800 Watts you get a lot of heat inside the case. I could have advised against an Air cooler earlier, didn't know you would go for 2 GPUs

>> The third point is that undervolting could help a lot, those cards use aggressive voltages out of box. Watch my video on the process, it will lower your temps by 10 to 15 degrees and this here is the easiest solution I think

>> For me personally I have one GPU in the first slot and the other GPU in the 3rd slot on the board, so there is a lot of spacing between them. I have my 2x 3090s SuprimXs heavily overclocked, they run at 65 degrees C at max
If you need NVlink you will not be able to use this configuration, you will need to use the first and second PCIe slots. Another note that the third PCIe slot uses x4 bandwidth Gen 4 shared with other devices, so you shouldn't install a second NVMe on your board.. but overall you don't lose any performance on PCIe Gen 4 x4, I have tested this extensively
You probably need a big case for this configuration
My setup is Here and here

>> There are more solutions with rise cables and an external GPU rack, or watercooling over which the cards become single-slot. I can give details over these if you want, let me know

The advice here is personal, this applies to everything I wrote in this thread.. undervolting is safe and all, you can never damage your hardware using AfterBurner, still the point is cannot give this kind of advice as a Chaos employee, proceed at your own risk.

Best,
Muhammed

Hi Muhammed, thank you for getting back to me so quickly. I really appreciate it.

Well as for the CPU heat sink being so close the GPU back plate, i dont think its an issue. When I benchmark with Cuda with both GPU and CPU, my CPU temp never exceeds 60c and the GPU temp is 73C.

I do want NVLink to expand the memory so the 3rd slot isnt an option. Plus I do use both M.2 slots. So I think my only option would be to get a blower style card. Either a Founders Edition or Gigabyte makes one. May have to get used though. But I think blower versions can be sandwiched. Another possibility like you mention is undervolting. I could undervolt a second FTW3 card. Because with my current case, which has 2x180mm fans blowing front to back, the second card temp was 83c. I didnt check vram temp but 83 I think was max for the card itself. But if an undervolt could at least keep it below 80c then that would be great. I dont even mind a slight underclock. It would still beat a single GPU. I dont have the second card anymore as I was exchanging my first card because prices dropped $300 so I was getting the same card at the new discounted price while i still could and returned my original card. Thats why i mention i have a second exchange window currently. Another option is getting a bigger Torrent case which adds 3 fans at the bottom under the GPUs.

Another thought was getting 2 Hybrid EVGA cards that have radiators and get a case that I can mount both radiators to. But i think i read somewhere that NVLINK might not be possible with dual Hybrid cards. And getting 1 hybrid and 1 FTW3 wont work since NVLink connectors wont line up. Why do they make this so complicated. Hopefully mobo manufactures will start spacing out the slots better.

Thanks again for your input. It's really helpful.

[Muhammed_Hamed]

Hey Sean,

Well as for the CPU heat sink being so close the GPU back plate, i dont think its an issue. When I benchmark with Cuda with both GPU and CPU, my CPU temp never exceeds 60c and the GPU temp is 73C.

It is, trust me. the heat builds up inside your case gradually until your CPU is chocked give it some minutes, the 5950X will get hottest when 2-3 cores are used
This happens in the Helios case, with 4x Noctua 3000 RPM fans.. and 2x 3090s SuprimXs, I had an air cooler before

So I think my only option would be to get a blower style card. Either a Founders Edition or Gigabyte makes one.

They will throttle as well, both of them will need undervolting to avoid thermal throttling
FE cards are good, great boards and cooling, Gigabyte on the other hand is horrible. the VRAM temps will be at +100 degrees
I suggest trying undervolting for both cards and improving the airflow of you current setup, the cards you have now are great!

Another option is getting a bigger Torrent case which adds 3 fans at the bottom under the GPUs.

Should be helpful, it is a great case

Another thought was getting 2 Hybrid EVGA cards that have radiators

The cards are very rare sadly, they should work fine with NVlink

And getting 1 hybrid and 1 FTW3 wont work since NVLink connectors wont line up

check if the cards have the same board, this could be possible. I wish we would have flexible NVlinks like the old SLI bridges in the past, it would make our lives easier

Let me know if you have any more questions

Best,
Muhammed

[Muhammed_Hamed]

Would you know which cpu does Phoenix simulations faster?

5950x is very similar to the 12900k in most cases

[sean_brown]

Hi Muhammed, thank you for getting back to me so quickly. I really appreciate it.

Well as for the CPU heat sink being so close the GPU back plate, i dont think its an issue. When I benchmark with Cuda with both GPU and CPU, my CPU temp never exceeds 60c and the GPU temp is 73C.

I do want NVLink to expand the memory so the 3rd slot isnt an option. Plus I do use both M.2 slots. So I think my only option would be to get a blower style card. Either a Founders Edition or Gigabyte makes one. May have to get used though. But I think blower versions can be sandwiched. Another possibility like you mention is undervolting. I could undervolt a second FTW3 card. Because with my current case, which has 2x180mm fans blowing front to back, the second card temp was 83c. I didnt check vram temp but 83 I think was max for the card itself. But if an undervolt could at least keep it below 80c then that would be great. I dont even mind a slight underclock. It would still beat a single GPU. I dont have the second card anymore as I was exchanging my first card because prices dropped $300 so I was getting the same card at the new discounted price while i still could and returned my original card. Thats why i mention i have a second exchange window currently. Another option is getting a bigger Torrent case which adds 3 fans at the bottom under the GPUs.

Another thought was getting 2 Hybrid EVGA cards that have radiators and get a case that I can mount both radiators to. But i think i read somewhere that NVLINK might not be possible with dual Hybrid cards. And getting 1 hybrid and 1 FTW3 wont work since NVLink connectors wont line up. Why do they make this so complicated. Hopefully mobo manufactures will start spacing out the slots better.

Thanks again for your input. It's really helpful.

Hi Muhammed, thank you for all the great input. I have a lot to think about.