BSODs

Just a regular 1TB external hardrive.

You know, I've run all these tests and nothings really worked.
But.. I think its just been corrupted video drivers.
I remember one day when it couldn't start, the boot up was changing colors.
Could that be another effect of a bad PSU?

The board has ati onboard.
When I checked driver sweeper, there was also nvidia chipset.
Is that for the card? Is it okay to sweep that?
Well I'm not sure but I sweeped the ati display.
And with that install of the gpu cd, things seem okay now.
I don't know about the usb boot up fail, but I can live if all I have to do is remove it.
I'll update if anything. Thank you for all the help. +rep

Update:

*my radeon hd 6850 came in, and I uninstalled old card, driver sweeped, installed new drivers.
Enjoying the upgrade

The computer's been running pretty stable.
But of course, there was a BSOD.
It only happened when I played Mass Effect 2.
I can not reproduce the problem with anything so far or any other games (like Dragon age 2, Sims Medieval, etc.)
Something of note, I couldn't play Mass Effect 2 without installing nvidia's physx software. So I installed it.
Could that conflict with ati drivers?
Looking into google, someone said people have had success by updating sound drivers.
Checked mine and it says it's up to date. Thinking of reinstalling them.

looking at blue screen view there is no bug check string description.
The only new information to report is that it says the cause is hal.dll
I mean, I guess can live without the game. But I just hope it doesn't happen with anything else.

Yes. But I do intend to switch the psu out when I can.
But you know.. it seems to be running okay? I've left the computer overnight.
Tested furmark. Done some uengine benchmarks. It was only Mass effect 2 when I hit a BSOD.
The first time it happened I was sad, but everything else runs good?
Been playing Dragon Age 2 on high settings for a couple of hours with no problems.
I tried Mass Effect and the same thing happened.

So.. I'm just guessing. Either a driver issue (I seriously think all my drivers are whack now)
Or is Mass Effect too demanding and was asking for more power than the psu could supply?

Seems to be working fine now after updating audio drivers.
Played Mass effect 2 with no problems.
Tried the Prime Tests and it works fine.

Then I remembered that I had tried to overclock before.
Seems that when I overclocked and I did the test, thats when it bsod'd
Blue Screen said something about an uncorrectable hardware error.
But the computer runs fine without any overclock.
So I am guessing that my computer is using just about the maximum amps the psu supplies.

I'm going to try to order a new one asap.
They don't have any corsairs here.
They had something like a 1000w greenpower one at around $200.
Checked online and it's about $100. Think I'd rather look for that corsair one you showed me again.

Thank you for all the help.
It's been a crazy experience, but it was fun testing everything and finally getting the computer to be stable.
Take care.