Visual display locking up, no response from GPU to monitor.

[AsianBob]

This has only started recently, and I haven't booted it up since for fear of acerbating the problem.
This computer has been running just fine for about 3 months now. 
I have a huge fan mounted on the side, a front and back fan for airflow and a pre-installed custom liquid cooling unit solely for the CPU.
2 GTX480's running SLI, a little close together for my comfort but after being reassured twofold by the tech and extensive tracking of the GPU temps, they've never run above 80C.
My motherboard is an Asus P6X58D-E.  I'm running Windows 7 premium 64 bit.  I have 12 gigs of corsair RAM.
My CPU is an Intel i7 extreme edition. 
I'm using WebRoot Internet Security Essentials and the Windows Security firewall.

To the problem.
I've been using the computer on and off.  Keeping it relatively free of dust.  I haven't even tried using it to "it's full potential" according to some of my friends.  Mainly, I just browse the web
and play a quick game of League of Legends.  I tried a Crysis demo, but got bored and went back to LoL. 
About 3 weeks ago, it locked up on me.  I'm not entirely familiar with these kind of things but nothing was responding, mouse, keyboard, etc. etc.
So I shut it off, and left for work.
Turned it back on, and boom, worked just fine for the better part of the day.  And it locked up again.  This time I noticed sound was still running from the speakers, and Skype was still running in the background because I could still converse with my friends.
I shut it off again, opened her up, checked connections, see if anything was leaking out of the liquid cooling unit, reseated the RAM, everything I've been told to do just in case a problem came up.
I rebooted, ran fine again for about 2 hours and locked up the same way.  I rebooted and whenever I would try to log in, it would load for a second, lock up, and signal would stop being sent to my monitor. 
I tried again, and the same thing.  Its locked up at this specific point several times and I gave up. 
Now, today, it will run about 2 minutes and lock up, display still up and everything.  I will try to log-in and it will lock up at the same exact point it was before, this time with no signal being sent to my display.
Nothing is abnormally hot.  As I said, the GPU's are the hottest things in there, but at max temps of 80C, I would just assume that's fine seeing as how Nvidias standard max threshold is 105C?
I just want to figure out whats wrong, if I've fried a GPU somehow, or my mobo's on the fritz.

[T-Rex]

Have you tried older/newer drivers for the card?

[ale52]

Can you boot into Safe Mode?

Alan <>< 

[AsianBob]

I haven't tried older/newer drivers for the card.   I haven't actually messed with drivers or anything of the sort at all.

And yes, I can boot into safe mode.  Sorry, you kind of fired up my memory there a second.  I was able to boot into safe mode, recover my documents and files onto a backup hard drive, and perform a system restore on my computer. 
I was wanting to format the computer, I am just waiting on a spare Windows disc.

[AsianBob]

I would edit.  I just can't figure out how.
Anyways, an update, and probably solved my own problem.
I took out the secondary GPU and I'm actually posting from the problem computer now.  I looked at the secondary in Safe Mode, dinked around and looked at resources and it mentioned it wasn't using any resources because it was experiencing a problem.
I guess its hosed? 
Or maybe just something screwed up in the registry?
I can't mess with it right now, backs a little off and this thing weighs a ton.  It was work enough just removing the thing, being seated right next to the other, I could barely push the tab to eject it out.

I have a new question now, how's the warranty on these kind of things?  Are they pretty lenient?  I mean, this is how it was built and presented to me, don't they have some fault in the matter?

[ale52]

Depends on how old it is.  Now-a-days manufacturers are warranting things for 90-days, some 1 year and some hard drives for 3 years.    

Lenient?  Depends on what side of the bed they got up that morning.  All you can do is contact them and ask.

Alan <><