Is this mobo dead-ish?

First off, these are the components I am working with:

Gigabyte 570 SLI motherboard
Visiontek ATI 4870 vid card
2x1 GB G.Skill RAM
2x512 MB G. Skill RAM
Western Digital 320 GB Sata HDD
LITE-ON DVD/RW drive
AMG Athlon X2 6400+

Here is the situation, I was reformating my drive with my Windows XP SP2 disk that I had used to previously install. Everything was routine until it got the "installing devices" mark at 39 minutes. I got a blue screen stop error. A google search of the codes returned 0 results. I figured it must be one of those typical windows flukes and I tried the reinstall again. Delete partion, reformat, install, blue screen. Three more times. Now I figure something is seriously wrong at this point. Since these were stop errors, I ran MemTest+ on the memory to find no errors. The funny thing is, it was a new stop error every time. Since Memtest came back clean, I decided to swap video cards, as maybe that was the memory culprit. Switching from the 4870 to a Zotac 8800gt an trying to install yeilded the same blue screen result at 39 minutes with a new error code. I then tried a fresh set of RAM modules just to be safe. same as before, failed install. Tried a different DVD drive, failed. Tried a new hard drive, failed.

Well that narrows down the choices quite a bit. The only culprits are my proc, mobo, and the install media itself. Since I didn't have a spare proc around, I tried a different OS disk. Mandriva One 2009 fails to load on the system as well. Everything goes fine until it just hits a black screen. No error codes, no blue screen, just a blinking cursor on a black screen. Next I tried a "vLite"-ed Vista disk I had handy. Vista installed on the system, barely, but is riddled with errors (other than the Vista ones). Errors such as blue screen stop errors when trying to move a file. Complete system lock when handling any large file. Error codes on Wndows Update. Blue screens on boot, random reboots, and complete system lock when trying to delete a file. In other words, unusable.

What bothers me, is that until last week, I had all three of these operating systems on here, installed from these same disks. No BIOS settings have been touched, no hardware was changed, no drivers were altered, nothing. I only chose to reformat because windows XP was feeling...off...somehow.

So basically, do you all think my motherboard is fried? If so, what part of it fried if I am somewhat able to get an OS going (albeit crippled with errors)? I have eliminated the HDD, DVD drive, memory, and video card. I don't have a network card or sound card, so all that is left is the proc/mobo.

Bad power, or bad hard drive, or high temp.

This same hardware configuration had been working for 3 months without fail.

I agree with clear cmos. Also suspect power supply.

I wouldn't thinnk the processor is suspect unless you couldn't boot. And I have had motherboards that refused to install an os, but their problems were more obvious. Its possible, but I would suspect other components first.

The stop errors do sound like a memory problem. Try winly's suggestion first, just boot with one stick.