Having had a quick read of the symproms....IMO
When you installed the sound card did you disable the onboard sound on the mobo...if it had onboard sound? as that will lock the pc up totally on boot up after the bios boots.
Yeah completely disabled.
If you had no onboard sound then does it boot up in safe mode uninstall the sound card as that could be faulty.
Or just remove the sound card totally and boot the PC up...does that work?
Soundcard was removed, no change. The card should be sound, and when windows did work, it had no issue, until i attempted to put the drivers on.
Couldn't get the thing into safemode as f8 is also boot order and there is a tiny amount of time before post screen and blank screen.

If it does not boot up then it could well be the GPU, are the sound and GPU card sat in the mobo straight? if they are even slightly askew it wont contact properly and will stop it booting.
All straight and fine.
There is a good chance that you have burnt the GPU but in such a short time it sounds unlikely as it usually takes a little longer..unless you have poor airflow.
It was probably 10 minutes until it died. As prior to the soundcad drivers attempting to be installed, i started adding some basic software.
If the GPU has burnt then yes it can boot up to bios then fall over as soon as the components get hot, if you dont need a great graphics card...as we talked about before...then get one with not cooling fan, cheap and cheerful, about £15in vat and p+p.
This is what i may do. After our little talk i spoke with the builder who was supposed to put in a faless card, as he had the 8500gt, less fan, for the same price. I should blame him if the gpu has fallen over!

But to me it doesnt sound like the mobo has fucked but either the sound or graphics cards, with it mor elikely to be the sound card.
The soundcard should be sound, it's bit of a motherfucker with it's own processors and stuff, but i have no reason to believe it doesn't work. Well, apart from the pc not working... Thanks for your help. I'm getting back in front of it within the next few hours and will be trying a load of diffferent things to see what happens. Not least waiting for the split second between the post screen and the attempted windows boot, to press f8. It's annoying that f8 on my mobo is also the bot order!
Overclocking has saved me a few hundred quid. I'm quite happy about that. The new heatsink only cost £15 including p&p and it allows me to overclock my processor by well over 1 ghz extra.
Fucking hell. That's one hell of an increase.
