Hello, in the future I am planning on upgrading my PC (I have one rtx 3090 now). I am not sure if I should get dual rtx 3090 connected via NVlink or one rtx 4090?
Yes I will have 48GB of VRAM with dual rtx 3090 but I don’t know if there is any NVlink out there to buy.
If two rtx 3090 are connected will I have 2x CUDA cores? I am not even sure if Blender Cycles are capable of that (two GPU’s rendering at the same time).
One rtx 4090 has 24GB of VRAM but I heard that in Blender it’s fast at rendering just like dual rtx 3090.
So yes, to sum it up, should I have dual rtx 3090 or one rtx 4090? You can tell me any pros and cons, I am mainly working on projects such as these https://vizioart.com/ which require tons of VRAM and fast renders are of a big help.
I can’t speak to the benefits of NVLink, nor to the advantage of one 4090 x 2x3090, but I can confirm that Blender will quite happily utilise dual GPUs (I have 2x1070) for rendering.
One 4090 will use less power overall- by a fair bit- than two 3090s. This will save you a lot of money over time. (You’ll almost certainly need a second PSU for 2 3090s, which will also cost you)
Technically one would just install a 1300W+ single PSU, maybe a little higher depending on the CPU, etc.
Apart from that, the only reason to get two 3090’s over a single 4090 would be the need to combine the VRAM, if you don’t need more then 24GB VRAM, then just get a single 4090.
If you do go for two 3090’s, try to get the 3090 Ti’s, reason being that the Ti’s have all the VRAM on one side only, where as the original 3090’s had half the VRAM on the backside of the card, and it gets HOT. If you then pack two together, then one is heating up the other even more.
Yes, I was afraid about that heating part. I already have one rtx 3090 so I don’t know if I could connect it with NVlink to rtx 3090 Ti.
Do you have any idea on how to efficiently cool dual graphics cards?
In theory you should be able to, having said that and given we are talking Nvidia here, I wouldn’t count on it. I guess at the same time they don’t even need to be the same make/model of 3090, but again, I’d want a solid ‘return’ policy with whoever you get the other card from, just to be on the safe side.
Yup, water blocks… haha
But outside of that, it’s really going to be case cooling and air flow. You may just have to have some beefy front case fans that pull in and blow some serious air over the GPU’s. This means either high noise all the time, as they run at full speed, or, you need to check your motherboard and setup and have it so that the main system fans speed up based on GPU temperature.
Most fans and systems are more configured to adjust fan speeds based on the CPU temp, but if you have two 3090’s rendering away for a few hours, it’s the GPU’s that are going to get hot, not the CPU. The last thing you want is the system cooling based on the CPU at 60C, while both GPU’s are at like 90C+.
Yes I agree about cooling and air flow. My case fans are configured to blow air based on my motherboard temperature. I bought a third front case fan for my Meshify fractal 2 XL case, only one fan will be at the back of the case.
Now I need to find out how to configure my case fans to blow air based on GPU temperature.
Thanks a lot for that Fan Control, it will help me in the future. Right now it’s not of a big help because it doesn’t support my motherboard chipset since Fan Control only shows fans on my GPU, my CPU and case fans (case fans are 3 pin) are connected directly to my motherboard but they are not shown in my Fan Cotrol GUI.
Nahh forget about it, once I get my 2nd RTX 3090 with new motherboard then Fan Control will work.
Right now I got some cheap 120$ USD motherboard called Asrock b550m pro4 (not so smart to connect rtx 3090 to it XD but I didn’t have enough money at that time). I will buy myself some pristine quality motherboard in the future so everything will be nice.
I’m sorry I don’t know. I’m on the lookout for a 4070 personally because of the aforementioned heating issues (most problematic with top end cards like 3090 if I understand correctly)
Yes most of the rtx 3090’s have heating issues, especially the Strix edition. Strix is clocked on a higher Mhz (it runs games better) so it heats up to 100°C while in Blender when it works on 100%, unlike in video games where it doesn’t run on 100% so there is no heating issues. I have MSI gaming X trio which is like third best, 2nd is EVGA and then is MSI Suprim at the 1st position (considering the cooling and noise).
I see, yes. I never considered that rendering would bring gpu usage to 100% whereas games are probably more variable in that regard. It makes sense to go with the better cooled cards.
I’m surprised by all the concern about temps on the 3090. Since my original reply I’ve sold the GTX1070s and replaced with a single RTX3090 FE.
I just did a test render, timed to 10 minutes (1,000,000 samples set, it got through 25,883) and the GPU maxed out at 71C. It didn’t hit 100% utilisation, either (ranged 97% - 99%) but that may be my own OSD rounding down (I use Linux, so we don’t have the fancy OSDs that Windows users get with the bloatware that comes from performance monitoring. Instead, I wrote a conky to get my OSD. Works with Steam games, too, though oddly, not with Unigine benchmarks in FS mode. It should stay on top of everything, but Unigine doesn’t seem to like that).
Oddly, whilst rendering on GPU, my CPU reached 81C, though rendering still seems to saturate one core/thread (Ryzen 5900X) so that’ll be it. Not a problem. Doesn’t throttle until 90C.
