PSU or MB?

[ste_bla]

Went to turn on old 939 PC, using every day for ~2 years. However today it seems to have slightly died;

* No beep (however not 100% sure there was before)

* CPU fan stays on full wack even though before it slowed down except when hot (via BIOS)

* Screen stays blank/stand by as if PC off

Is it likely to be PSU or MB or GFX?

Also cant see any 939 mobos , if i cant find the same one does this mean i have to wipe my HDD which I haven't backed up or can i bodge a new install

 

[Ast3r]

Probably MB,RAM or CPU.If the PC has 2 sticks of RAM try to run it with only one.

Also cant see any 939 mobos , if i cant find the same one does this mean i have to wipe my HDD which I haven't backed up or can i bodge a new install

Its not necessary to do that.You'll just have to remove the old drivers and install the new mobo's ones.But you could get conflicting issues if not done properly.Sound drivers are the most common known to conflict.

 

[Destination]

Try resetting CMOS on your BIOS first.
It might be as simple as the battery failing and thus it fails to POST.

Usually when amachine is swictehd on, the fans go at full speed for a couple of seconds until the BIOS takes over and tells them to slow down.
It sound slike you are not POSTing, and probbly due to some MB issue.
I'd check that first.