AMD Radeon™ HD6490M drivers hanging Starting Windows Screen (laptop)

Hey guys. This is a pretty detailed explanation of what's been happening while skipping over the petty details.

On the web, trying to order take out, suddenly the screen goes black, fans go into overdrive and continues like this for about 20 minutes.
Hold down power button to fully shut down and then restart. On restart, system hangs at "Starting Windows" screen and again, fans go into overdrive.
Eventually, after a million way of trouble shooting - find out it was the video drivers causing the issue. HOWEVER no matter how many times I removed old drivers and installed new ones the problem persists and eventually, decide to completely uninstall and do a clean install of Windows 7 Enterprise.
After the clean install, attempt to install drivers once again and it begins causing the same issue - hangs at "Starting Windows" screen and fans go nuts! Decide to just soldier on and go without pretty graphics.

Honestly, though, not being able to play any games means this laptop has essentially become an unwieldy tablet for all intents and purposes.

My suspicion is it may be a bad PSU causing the issue by not powering the motherboard enough to properly run the graphics card. Does anyone else have any ideas, though? If it IS the PSU, being that this is a laptop and all, are there any realistic/cheap options for repair? I've repaired internals of my previous laptops before but nothing as vital as the PSU. Are there any programs or utilities out there that I might be able to try to I don't know... Maybe direct power towards the graphics card instead of some of the 7 processors? This was my boyfriends OVERLY powerful laptop but after it crapped on him, not being at all tech savvy, he said I could have it and as its a $1200 2yr old laptop, I am determined to do everything I can to salvage it.

Thanks for any help!