Windows won't start after CPU upgrade

[Matt1970]

Arent Q9X50's all 45nm?

That might have been it. Intel lists his processor as 45nm.

http://ark.intel.com/products/35428/Intel-Core2-Quad-Processor-Q9650-12M-Cache-3_00-GHz-1333-MHz-FSB

 

[Termie]

That might have been it. Intel lists his processor as 45nm.

http://ark.intel.com/products/35428/Intel-Core2-Quad-Processor-Q9650-12M-Cache-3_00-GHz-1333-MHz-FSB

I assume the OP had already checked this.

In fact, the last BIOS update for the P5W DH was in 2010, long after the q9550 was released:
http://www.asus.com/us/Motherboards/P5W_DH_Deluxe/HelpDesk_Download/

It's a virtual certainty that Asus added support for 45nm processors among the many updates to the BIOS on that ultra-popular board over the four years it supported the board.

 

[IGemini]

Arent Q9X50's all 45nm?

Doesn't matter anyway. I did the exact same upgrade path as the OP and I got a Q9650 running on my P5W DH without doing anything beyond BIOS upgrades. Only downside was the CPU overclocking settings were locked...as in completely invisible.

I do believe that later hardware revisions of the board had a modified voltage design, which is probably why they put Yorkfield support in beta. So it's really a crapshoot if it works or not.