Paul P :
For the cooler I've chosen the
Zalman CNPS20LQ radiator, which is very much like the one Intel offers for the LGA2011s.
I don't know much about water cooling, but that looks quite substantial. I like how it's pre-assembled. If my downward-blowing cooler turns out to be insufficient, I might try something like yours.
You can probably find reviews where it was tested on an overclocked i7-3960X or something. If it can cool that thing, your E5-1620 should be no problem.
I did find one review on a French language site where it was included in their testing on a FX-8150, stock & overclocked. The only problem with their data is they didn't subtract off the ambient temperature, though they did list the ambient temperatures for each test, which varied by as much as 6.5 C (with your cooler being tested on the hottest day).
If they controlled for ambient temperature, your cooler still would be a mid-to-low performer, but the FX-8150 has a TDP of 125W and the Zalman CNPS20LQ cooled it to very acceptable levels, at stock clock. 47 C (absolute), to be precise. My Pentium 4 ran at up to 65-70 C, under load, and that PC lasted 8 years and still works.
Paul P :
What memory are you using with your E5-1620 ?
I temporarily cannibalized DIMMs from a random machine that happened to work. [strike]I'm planning to order 4x Crucial CT51272BD160B 4GB CL9 Unbuffered ECC DDR3-1600 DIMMs.[/strike]
Edit: Do not get this RAM. It is 1.35V memory, which E5 Xeons will not support above 1333 MHz, regardless of the DIMMs' specs. If you want your DDR3-1600 to actually run at that speed, you should stick with 1.5V RAM, single or dual-rank, and only one DIMM per channel. See: Intel® Xeon® processor E5-2600 product family UDIMM Support (pdf) (that's for unbuffered - there's also a similar doc for registered).
The main thing is to ensure your board supports registered or unbuffered, depending on which you bought. Besides that, I think voltage is the only other nonstandard aspect of DIMMs to worry about. Intel CPUs like a different voltage than AMD, but I forget which is which. When in doubt, get the "Intel Certified" version, if they make one in that product line.
Paul P :
It's not on Asus's qualified vendors list so I guess I'm taking a bit of chance.
Does Kingston have a memory finder on their site? I think memory vendors are much more aggressive about testing board compatibility than board vendors are about testing memory compatibility.