Nvidia brings liquid cooling to A100 PCIe GPU cards for ‘greener’ datacenters Nvidia's GPUs are becoming increasingly more power hungry, so the US giant is hoping to make datacenters using them "greener" with liquid-cooled PCIe cards that contain its highest-performing chips. At this year's Computex event in Taiwan, the computer graphics goliath revealed it will sell a liquid-cooled PCIe card for its …
I have an RTX 3080 and, although you might say that it is air-cooled, there is still a bunch of liquid in there to get the heat from the GPU to the fans.
I wonder how that will work for the datacenter. For the moment, the A100 doesn't seem to be liquid cooled, but it sure is outrageously expensive.
"looking at liquid cooling as a way to cut down on energy consumption"
Assuming that the laws of thermodynamics didn't change whilst I wasn't looking, just how much truth is there to this? In terms of energy expenditure, just how wasteful is air cooling?
The same amount of heat energy has to get moved from A to B, regardless of the medium.
My guess would be that the efficiency increase is due the the fact the the cooling liquid transfers heat more easily between the chip and the coolant. Air is not very good at conducting heat. A lot of energy goes into spinning the numerous fans in a server, where one small pump can move the cooling liquid.
Also, think about how much quieter a completely liquid cooled data center would be to work in.
Exactly this. Water conducts heat much more readily than air, and can hold a lot more of it, requiring significantly less flow of the cooling medium (in this case water vs. air). So instead of using 100W/server or more on spinning fans (which are also contributing to the heat load), you can spend 4.3kW to move warm water for an entire row of cabinets (using something like the CoolIT CHx750 CDU, which claims to handle up to 750kW heat load). So, if you figure 4.3kW to cool 750kW of server load, that's about 0.06% of power going to cooling, vs. 100W of fans to cool a 600W server, being about 16.7% of power going toward cooling. This is only looking at the server side of things; the facility side is similar as they only have to pump water through mostly-passive coolers, vs. moving around a lot of air through active chillers. Due to the thermal characteristics of water it can operate as a sufficient coolant at much higher starting temperatures than air, adding to the efficiency. I believe something like up to 45C is allowed on the *inlet* side of the server, outlet side can go up significantly from there, which means a passive cooling tower in outdoor ambient air can bring it back down to useful temp in most climates (maybe not in Arizona in the summer, but in most northern climates it's perfectly reasonable).
In simpler terms, you need to cool the air much more and move more of it to get the heat transferred from the chips. You then need to compress the air to heat it up to get the heat out of the air into the environment, you then need to cool the air to start again.
Water can pretty much flow in at room temperature, get heated to chip temperature, flow out, get cooled back to outside air temperature and repeat.
Forgive me if I have missed something here.
Compute and storage (chips and all the gubbins that make up this stuff) produces heat, often lots of it, usually to the point that the required cooling is not far off the input power to the equipment.
So liquid cooling may mean that you can possibly get the heat out of the chips more efficiently so you can load the more (HPC is doing this regularly now) but you still have to get rid of the heat and the simple physics of this does not really change the efficiency.
There will be heat exchangers and pipes already with chilled water, you just have another loop for this and the coolant in this case often has nasty chemicals in.
This sounds like a typical greenwashing to make something sound better than it actually is.
The bottom line is that it does not matter how you try to zazz it up, data centres & IT are never ever going to be "green" or environmentally friendly. There is simply too much power, resources and short life-span in the chain with very difficult recycling at the end.
It's still the same amount of heat that you have to get rid of. Whether you extract that heat, at source, with cooling air, or with a liquid coolant, you still have to get that heat into the air. Being the final dump in all but a few locations. So, all you have added is yet another power requirement. Albeit in a slightly remoter location. So, a more complicated system, with higher power requirements.
This is about the efficiency of moving that heat from the server chips to the chiller plant.
Air-cooled means big fans in the A/C cold outlet to cool air and blow it into the cold aisles, big fans in every server to blow lots of air over the heatsinks, and big fans to move that hot air out of the cabinets and through the A/C intakes to transfer the server heat plus all the fan motor heat into the chiller warm water feed.
Liquid cooled replaces all those fans with a far more efficient pump, that has to move far less volume of liquid.
On top of that, you don't need the chiller to cool the liquid to as low temperatures as the air-cooled, because the heat transfer is so much more efficient. That makes the chiller far more efficient as the temperature difference is greatly reduced. In many climates you might not even need a chiller at all, as your "cold water" feed can be 20 or even 30C, so much higher than ambient.
The difference is several orders of magnitude, assuming you've got a lot of servers.
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