System unstable please help!! Power??

That's a hard one it could be alot of things.
could be badware?

you sure you have a good os install?

get a low end graphics card see if that helps. if its the psu you might use the adapter that comes with it to cross load your 12v rails.

see if your psu runs off 1 rail or are they joined for the 12v. That card is power hungry and your psu is really questionable as you suspected.

you might try increasing the voltage on the ram and cpu and locking them if its auto. when does the freeze occur - you need more details to solve this?

Quite possible that the PSU isn't giving you enough power. I assume the 75 GB drive you have is a Raptor.

Try taking out a stick of memory, disconnecting everything but your boot drive and your motherboard power plugs. Leaving your GPU connected, try booting and running some stress tests.

If you have an older video card, stick it in and see if it runs stable. 2.88v on the 3v rail is pretty low, but your PC won't draw much power from there.

Will a SEASONIC 700W PSU suffice?? I am going to upgrade.
THX (I do not have a old PCIe card to test).

I calculated 39A per ea 12V rail which would be adeuquate this PSU. I hope this is right. THX. Physics was long ago!!

I think the old psu was bad or at least on its way out with that low voltage reading. Either case, the Seasonic 700wt should be good enough for powering a new DX10 card. Good choice.