I acknowledge that our hardware is different that that probably makes some contribution, even a significant one in the case of the CPUs, but I'm absolutely sure that the difference in stress testing is the biggest difference. A memory check is barely going to touch the CPU. If you are comfortable with that for your own use, that's fine, but calling it "max load" is incorrect. I don't mean to harp on you for your own decisions, but it just needs to be made clear for anyone who comes along and sees this later--modifying cooling without doing a proper stress test is dangerous.
However, I do not believe I'd see much different temperatures. Nothing close to the numbers you are posting, simply because of the quite different hardware circumstances our systems possess.
Like I said, you barely touched your CPU with that memory test. I don't know what your background is, but it seems naive to me that you would acknowledge that you don't care to test beyond 20% CPU use, but dismiss the temperature differences as due to hardware differences. I think you're wrong about that. Maybe they won't get as hot as mine but significantly higher. Run mprime set to max CPU and see for yourself if you'd like.
I doubt the drives had much to do with it, as they were all sitting idle, but maybe if I'm bored later maybe I will repeat the test with all the drives pulled just far enough out to be disconnected.
In my box, 3 fans were powered from the front backplane and three fans from the back backplane. The last fan was connected to the motherboard.
Oh, ok. In my box, the 3 back fans and the one in front of the PSUs came from the seller connected to the motherboard.
@taylornate btw - when you're discarding any differences from covering the back and side ventilations, during what test did you draw that conclusion?
I'll add in advance, the benefits I experienced were related to drive temperature and an 'empirical pragmatic' steep increase in air pressure in front of the 24 caddies (where my drives were mounted). Ie, pressure was not lost to the side vents, nor the rear backplane which - CLEARLY - was the case prior the mod.
This was during the mprime max CPU stress test. When I undid the covering of the rear bays, there did not seem to be any notable difference to CPU temp or fan speed. Based on the geometry, I would expect air flow across the front drives to increase without the covering if there is any change at all. The only difference the covering would introduce is to divert air flow from the rear drive bays to the CPU, memory, etc. When I uncovered the side vents, I noted that fan speed (noise) decreased significantly, as the CPUs got better air flow. I will admit that this would decrease air flow across the front drives. I'll also admit that I haven't been very concerned with heat from the drives, and I'll have to investigate that further before putting the server into production.
Update re: virtualization...
Looks like I will actually need to pick up a RAID card for a mirrored pair, not necessarily for the ESXi installation, but certainly for the data store. Kind of a bummer, but I think it will be worth it. My current plan is to pick up a lsi 9211-4i which will fit into a 4x PCI slot, leaving my remaining 8x slot for a 10Gbe card. Any comments appreciated.