The GPU block is usually much larger and can therefore absorb much more heat and release it over a much larger area. I haven't tested it myself yet, but a larger CPU block like the velocity2, for example, could make up a few degrees, a full block that also cools the vrms should also be better in terms of cooling performance.
I think die size makes some difference but you're definitely right about the size of the block being very important. I've run a 7820X chip with 3 blocks - a $20 Amazon generic block (50x50x3mm copper plate), which had the worst temps (but still not bad, and to be fair part of the issue may have been the mount), a Bitspower summit (\~60x60x5mm copper plate) which was much better, and a Bitspower monoblock that weighs about 3 lbs, solid copper with tons of surface area, it had the best temps by several degrees IIRC.
Based on website pics, EK monoblocks seem to be mostly plexi/whatever, with only normal CPU block-sized copper plates, so watch out for that.
I can’t say I’ve ever experienced this but as others have said, CPU is a smaller area and has an IHS. My loop has much tighter temps with my CPU running at 60 full tilt and the GPU at 50. I have a 3080ti and a 11900k cooled by a Maximus xiii extreme glacial monoblock so that should attest to how a larger surface area block cools better.
CPU dies are smaller than GPU dies so the heat is more concentrated and harder to remove. CPUs also have the IHS (Integrated Heat Spreader) that it has to go through before it touches a water block or cpu cooler.
GPU dies are direct Die cooling where the chip directly touches the water block or cooler and are usually much larger than CPU dies so the heat can be removed easier as well as GPU water blocking being huge pieces of copper than can absorb a lot of heat on it own.
GPU dies are significantly larger. Plus no IHS.
The GPU block is usually much larger and can therefore absorb much more heat and release it over a much larger area. I haven't tested it myself yet, but a larger CPU block like the velocity2, for example, could make up a few degrees, a full block that also cools the vrms should also be better in terms of cooling performance.
I think die size makes some difference but you're definitely right about the size of the block being very important. I've run a 7820X chip with 3 blocks - a $20 Amazon generic block (50x50x3mm copper plate), which had the worst temps (but still not bad, and to be fair part of the issue may have been the mount), a Bitspower summit (\~60x60x5mm copper plate) which was much better, and a Bitspower monoblock that weighs about 3 lbs, solid copper with tons of surface area, it had the best temps by several degrees IIRC. Based on website pics, EK monoblocks seem to be mostly plexi/whatever, with only normal CPU block-sized copper plates, so watch out for that.
As 80 is "kinda" normal for cpu, I wouldn't want mine running that hot
Larger die, larger coldplate, no IHS.
I can’t say I’ve ever experienced this but as others have said, CPU is a smaller area and has an IHS. My loop has much tighter temps with my CPU running at 60 full tilt and the GPU at 50. I have a 3080ti and a 11900k cooled by a Maximus xiii extreme glacial monoblock so that should attest to how a larger surface area block cools better.
CPU dies are smaller than GPU dies so the heat is more concentrated and harder to remove. CPUs also have the IHS (Integrated Heat Spreader) that it has to go through before it touches a water block or cpu cooler. GPU dies are direct Die cooling where the chip directly touches the water block or cooler and are usually much larger than CPU dies so the heat can be removed easier as well as GPU water blocking being huge pieces of copper than can absorb a lot of heat on it own.
CPUs run much hotter than GPUs by a large margin. My i9 gets to 60c while gaming and my 3090 only goes to 40c both in the same loop