Artifacts in POST and BIOS, none in Safe Mode, OS will not boot normal

Here are the symptoms:

Problem started when the computer stopped being able to run programs like Team Fortress 2 and Steam. Programs like Skype and Chrome still worked. Within the next 24 hours, Skype and Steam also began to experience issues. 24 hours after that, Windows ceased to boot.

Issue persists even if one stick of RAM is plugged in and I have tried multiple slots with different sticks of RAM.

The dots go away if the computer boots into anything beyond the POST. Even on the text POST screen and the BIOS, all of the characters are slightly deformed (consistly deformed, every single D has a small line through it in the same place) and also in the BIOS.

The computer will not boot into Windows, but will boot into Safe Mode. Safe mode is stable, people were able to do things in safe mode for at least an hour. I know my mother was playing Popcap games on it during this time.

I cannot boot from USB anymore. It hangs with a blinking cursor at the screen where it initializes all the SATA devices and never actually boots the USB drive.

When booting from DVD, there is a several minute lag time before it can spin up the disk again. This makes booting off any DVD painful. Once it spins up, though, it runs perfectly fine. We also replaced the DVD drive right after the computer started having issues.

Screen has gone black to a blinking cursor once during a Windows install before. We are currently in the process of trying it again.

Using the DVD drive on different SATA ports does not fix the issue.

CPU temps are fine. GPU temps are fine.

Problems persist even with the hard drive unplugged.

"sfc /scannow" in safe mode does not resolve the issue, but it always finds files that it says are corrupt. "chkdsk" does not fix the problem as well.

Clearing CMOS did not fix the problem.

I do not currently have a spare video card to test.

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What do you all think is going on? This is about a 6 year old Core 2 Duo desktop. I am currently trying to get Windows re-installed on this computer from the ground up to see if it will even run Windows after POSTing, but I'm not sure if the problem is PSU related (650W Antec Trio, it has more than enough amperage on the 12V), motherboard related (the artifacting in the ASCII characters is consistent, but there is no artifacting after POST), or graphics card related (artifacting makes me think of the GPU first).