UPDATE Thanks for all the replies so far... I got a new bios battery - didn't help. Found a speaker, on the occasions it does boot, it gives a short beep and proceeds through the boot process. When it doesn't post, it doesn't beep at all... what does this mean?
True, I expect no beeps to mean either cpu or ram is causing post failure... however, when it does boot (usually after leaving the psu switched off at the wall for a while) it displays everything in bios fine. However, everytime i have got it working recently, the bios has reset its self to default settings, when i change the time and date and reset it, it goes back to not posting... could some of the default settings on the bios be causing this?
Right, Flashed the bios, same version but thought i would do it anyway. Booted ok. Loaded windows ok. Restarted, changed time and date in bios F10 save and restart... doesn't post... arrrgghhh!!!! Any suggestions?
