I'd upgraded to a new machine some time ago, but figured it was too much of a waste just letting my 790i sit-idly-by collecting dust when the combination of my Qx9650 + old EVGA 250 GTS are still amply viable by today's standards. I went ahead and allocated a random chassis I found to utilize the components, but didn't have a spare power supply laying around to get it up and running. I finally went ahead and took care of that last night though--so basically the computer was unused for about two months (since I initially replaced it). I stole the RAM stix off of it (for my new build) and replaced it with some old Memory modules I had hidden in a box for the longest time (from when I originally built the computer six years ago).
The computer booted up and worked great! The only downside to it from the (new) get-go was that the temperature read-outs weren't what they used to be, but it isn't a problem because I am not planning to O.C. it or any thing of the sort (the CPU basically runs around ~45^C).
The CPU is 1333MHz 3.0GHz
MoBo FSB is 1333MHz
& RAM is 4x1GB 1333MHz 9-9-9-23
Everything was working perfectly well. Now though however, it's having a problem... and I can not for the life of me figure out a plausible solution to remedy the problem. **I had finished "rebuilding" it last night and went ahead and ensured the BIOS were configured to a good setup and then installed the O.S. and confirmed everything to be satisfactory and functioning properly. I went ahead and configured the system in the O.S. (Chipset / Drivers ; Updates /etc.) and total had re-booted the system some (maybe) several times total last night and 100% had no apparent issues. I did not bother running a stress test to confirm system stability due to the "higher" than previous temperature read-outs, but I didn't suspect it to be a problem.
I don't know what the problem could be, but now after I push the power button the system boots to the post screen and as soon as it says "Testing Memory"(*) it hangs. I don't think that the system freezes-up, it just doesn't continue booting. My suspicion is that something is wrong with one of the RAM stix, but my system was working just fine last night ... I can't figure it out at all--what I should do that is.

I tried that, I even removed the original RAM stix from my new(er) build and attempted testing it with all 4 of them 1 at a time (8 sticks total) ... I don't know what the problem is ...
 
On the plus side--I don't know what happened, but I turned it back on after about three hours after "giving up" and it decided to pretend like the whole incident never happened and now is working just fine.
 
790i FTW (132-YW-E179) + Qx9650 + Zalman CNPS9500 + EVGA 250 GTS + 4x1GB 1333MHz RAM (9-9-9-23)
VCore 1.2 & Temp's ~50^C (peaks around 48^ when not at 100% & ~59^C when @ 100%) ... Any suggestions what I could / should do for better temp(s)--or is this combination plenty good as is. (except for maybe increasing the RAM to 8GB someday)
 
***Hopefully this weird phenomena of "Mem Testin ..." (hang) never occurs again***

If you ever decide to go 8 GB, get the Patriot 2 x 4 GB DDR3 1600 PSD34G16002H (available at newegg). I've had them in for years now. They're rated at 1.7 V, which is not quite as high as the board is designed for, but I've had my MB linked & synced at 1600 w/ my Q6600 running at 3.6 GHz for quite some time.
 
I think they're about $50 for the pair.