mobo or psu?

[nmnget]

I've searched through threads and couldn't find a clear diagnosis. Anyways I woke up one morning about a week ago to find that my pc won't start. I switched off the psu and then back on and didnt get it going til after a few repeated attempts. One of two things happen when I try get it started though; 1, the pc fans spin for a few seconds and dies but psu, hds, and mouse are running or 2, the pc fans run really fast and psu, hds, and mouse are running also. Days go by and it takes longer to get my pc to fire up until a few days ago where I couldn't get it going at all.
No forced shutdowns no bsod. Tested all my ram sticks and each slot, tested gpu with onboard grapics gpu, tested psu on another less demanding rig and it booted properly. I then tested the bare mobo and I notice that I get the same beep with everything in it. With various components, its still the same single short beep.
HP pavilion a6700f Phenom X4 9150e
XFX HD Radeon 4740
Cooler Master 550w
4x(1)gb Ram
3 hdd (500gb, 100gb, 120gb)

 

[Peter.Cort]

with that board a short beep on post means the post is ok.

does it boot normally with onboard graphics, some ram and the boot drive?

 

[nmnget]

i thought it was post too, but it made the same beep with no ram and usb ports unplugged


it does the same thing with onboard graphics, boot drive, and some ram

 

[MindoverMaster]

Might be a board defect. Did you try resetting BIOS yet?

 

[nmnget]

yeah, i tried resetting it already, no luck.

it's been working perfectly since my last gpu upgrade 13months ago

update: just tried a new psu and it's still not booting. i'll look into getting a new mobo or a mobo-cpu combo unless somebody can tell me otherwise.

update 2: tried booting with one stick of ram, boot drive, and onboard graphics. now i get no POST beep and my boot drive isn't running. boot drive does run on old rig.