Celeron D to a Pentium D = CRASH AND LOCKUPS!

[myequation]

MOBO: Gigabyte 8I865GME-775
RAM: 1g kingston dual channel
PSU: tHERMALTAKE 500W W0120
full psu specs at this link: http://www.thermaltakeusa.com/produc...0120/w0120.asp

HD: WD 120 GB / WD1200JB-00GVA0
OS: XP SP2
Display card: NVIDIA GeForce 7600 GS AGP

Okay here's my issue I built this PC about 9 months ago.
My original cpu was a Celeron D 351 3.20Ghz, it was slow
This pc was stable, never had a single crash or reboot, during the many hours of use.


Yesterday I installed a Pentium D 935 dual core Presler 3.2GHz.
Wanted to speed things up a bit, found a good price at newegg.
My pc booted up fine, recognized the new cpu and loaded xp (sp2)
but....
I started getting random reboots and lockups. Sometime within 2min other times a few hours..

After the first reboot I started using a program to watch the cpu temps, I never saw it above 41c


So what could the reboots be from?
Would the CPU upgrade draw more power and make the psu fail?

I used Prim95 and other stress test programs to heat things up, things run fine (only tested for an hour)
Ram was tested with memt86 or whatever it's called?

I've used software like speedfan to watch everything,
Things look perfect temps, etc. even down to the Voltage coming from the PSU.

I even touched the CPU Heatsink after some of the crashes and it seems normal, everything seem to be within it's normal temp
And I'm using the correct Bios but all versions have been tried.

I'm stumped

[JAC]

Put the old cpu back and and check everything.

Latest bios updates for your mobo?

Tried all the default settings on your bios?

Have you web searched for any problems with this motherboard and cpu combo?