Pc wont boot after windows 7 update, not even bios

[c4charlie]

I've had pc for several years, never had a problem. However, last nite i updated windows and restarted. But it wont boot up. Cant remember what the update was for but they're the latest ones.

I can turn on the pc, the screen displays the mobo logo and press del for efi bios and it just hangs.

Case fans, cpu fan, gpu fans all spinning, RAM lighting up(tactical tracer) not red led.

I've reseated cpu

Tried i stick of RAM in each slot

Cleared cmos and had battery removed for over an hour

Checked all connection, looks good

P8Z77V-LK
I5 3570K
8GB Crucial Ballistix (2x4GB) DDR3
GTX 670 Gigabyte windforce
500GB Seagate
Corsair CX500

 

[CountMike]

One thing is sure, no OS update can do that. It should BOOT up to BIOS even without any OS or even a drive. Try without HDD just in case it died.