Well, after RMA'ing my mobo, I had the same problems I had before, and found out by swapping to my stock fan on my CPU, I fixed my mobo not going to POST. I don't know why I didn't try that before wasting a month of my computers life, but I learned something new.
I noticed that pressure applied to my CPU by the stock fan is greater than another one that uses screws as a locking mechanism. I am just curious as to why the pressure applied on certain CPU's affects if a mobo will POST or not.
I realize this will vary on different mobo's or it may be that only I have this problem, but I want to know how it works?
My current theory is that even when you lock your CPU in, it is not in sufficient contact with the socket, and that a certain amount of force is required to push it in far enough.
Any other theories or known causes?
AMD Phenom II X4 965 BE @ 3.4GHz
Overclocked: Not now
GIGABYTE GA-MA770T-UD3P MoBo
XIGMATEK Gaia SD1283 120mm CPU Cooler
SAPPHIRE Radeon HD 5770 1GB 128-bit GDDR5 PCI Express
2 x G.SKILL 4GB (2 x 2GB) 240-Pin DDR3 1333
HITACHI 1TB 7200 RPM SATA Kard Drive
Sony Optiarc 24X DVD/CD Rewritable Drive Black SATA
APEVIA X-DREAMER3-BK Black Metal ATX Mid Tower Computer Case
APEVIA JAVA ATX-JV650W 650W ATX12V Power Supply
the "no post" problem maybe was due to loose cpu fan connection or broken fan.
my motherboard has CPU fan failure protection when fan is bad or gets unplugged or stuck it will not boot PC
Pressure got nothing with PC posting or not. \ in case of really loose contact CPU will simply overheat.
The more likely reason is bad cooler installation that lead to motherboard leads cracking so when you apply pressure it "fix" the problem.
The CPU and Socket got its own tension and locking mechanism once properly installed it does not need any help from CPU cooler, (
It's easy to damage motherboard with huge aftermarket coolers when your pc in vertical position.
I once lifter back end of PC to hook up sound, it slipped and dropped about 6 inches on hardwood floor, my ~500g tall heat sink ripped guts out of motherboard where it was attached
*maybe if you can take good close up pictures of your PC insides around the CPU and post, some1 might spot something that might help you.
My feeling it wasn't a pressure issue in so much as a metal backplate causing a short. The XIGMATEK Gaia SD1283 AM3 backplate is metal and both the top and bottom installation 'should' have "insulating washers".
If the backplate is coated with a non-conductive plastic/rubber then make sure that side is in contact with the MOBO and there's no exposed metal or protruding parts off the MOBO backside. The pressure should not exceed finger tight and too much or too little thermal isn't good either; 'rice' size 1/4" thin line.