Hi there,
another great adventure for me and obviosly other problems that make me write here like always, old-hardware experts!

So I decided to find this motherboard to try to benchmark and play games on an high-end desktop and compare with my LGA775 Q9450 Windows XP installation.

So, as all of you know, this motherboard is an AM2 socket mobo, and after reading in Asrock site, I found for only 20 euros a great Phenom II 965, that is supported as wrote in SUPPORT tab.

I have another AM2 processor, a nice dual core 4200+ 2,2ghz CPU.

With this CPU system boot immediately, and it work flawlessy. With the Phenom II system won't boot at all. No beep codes, no monitor signal.
After that I tried to replace another time the 4200+ and it starts. So I make a tour in bios and I try to set something to make the motherboard more "ready" to the Phenom II.

After some trying, it boot. I can see the bios, is the last version, and it is correctly recognized as it should be. A Phenom II 965 3,4ghz. At that point I decided to set bios better, I disabled things that I don't need, I put the overclock in Manual mode, and I set the 1,45v. on the CPU.
I shut down and I start, all was ok. I installed Windows XP, all gone right. I was happy cause I thought I had solved my little initial problems, I tried a little overclock too. My Phenom II reached 3,6ghz with 1,425.v I don't want to stress it so much. (Anyway probably I am video card limited considering AGP slot and with a 9800PRO and a X1950PRO this Phenom II is probably too fast).
So I make other boots, all ok, I tried to setting the RAM more powerful and I reached with ADATA Vitesta Ex. Edition the 1066mhz. (the RAM is signed at 800+mhz, but in reviews it is demonstrated that always can run at 1066mhz on 5-5-5-12).
All runs fine, games runs fine so I decided to find a case and put all the great hardware inside. (look at the photos attached).
This morning I made a nice work, I packed all inside the case and after about one hour of nice happy work, system WON'T BOOT ANYMORE.
I am surpised, how can the day before working so good without any issues, and after some start and stop all seems working fine. I closed the system too for about one hour and when I rebooted all was ok.
Today it decided to not to run, after I unplugged the power cord some times in one reboot system started fine but after I set the bios another time it never boot anymore.
So this evening I'm here to try to understand WHY before of all, and try to find causes with you.
Some of you have any idea?
Tonite I swapped the Phenom II another time with the 4200+ x2 and it worked like a charm, immediately.

Now I'm in the bios.

There is some setting that I HAVE TO FIX or SET before plug the Phenom II another time? Do you have some advice?

It is probably a motherboard power supply problem?

I plugged all the cables, I have a nice Enermax FMAII 460W power supply, and yes, the battery of the bios is in perfect shape (3,1volts).

I am looking for a nice advice, for the moment I attach you some photos of this old/new system, very weird but effective. A nice fast-ultimate Windows XP machine!!!