XPS 430 Keeps Freezing, upon reboot boot drive not recognized sometimes

Last week I added a SSD and new video card (AMD HD 7770) to my personal PC (Dell XPS 430  Core 2 Duo Quad Q8300 2.5 ghz 8gb RAM). The power supply is 425 W and according to specs should be adequate for the GPU. In addition to the SSD I have 3 other HDD’s and a DVD burner in the box, but the SSD is the boot device.

 My PC has run fine all week until Tuesday night. When I am doing something kind of video intensive the PC freezes completely and just hangs. (I had been doing the same type of stuff on my PC all last week, so this wasn’t a new heavy load for it) Upon reboot, it may or may not recognize the SSD as the boot device. When it doesn’t recognize it, it will after a reboot or two. When it froze the first time, I was capturing a streaming video feed from Youtube and I was editing video in Pinnacle. When I am doing something graphics intensive the PC will run for 5-10 minutes without freezing, if I’m just browsing the internet or not doing anything special or it’s idle, the PC is fine and doesn’t freeze.

 I was thinking originally it was the video card, or the PC was overheating, but it’s not hot inside, and it doesn’t explain why the SSD isn’t recognized sometimes. So I don’t know if it’s a bad SSD or the video card, or my PSU is going to heaven….or?

 So…. I got a 600W PSU last night. Installed it…. Same thing. (Freezes with any sort of load after about 5 mins)

I put in my old video card (AMD 6670)…. Same thing.

With the old video card in, I unhooked all the other drives except the SSD…. Same thing.

I took the SSD out of the equation and installed Windows 8 on a different HDD with old video card and nothing else plugged in… Same thing.

I thought maybe it was Window 8? So I installed Windows 7 on the HDD…. Same thing.

I ran a stress test on the PC, and it freezes up, so I get no test results. I ran Dell PC Doctor, it freezes on the Video Memory Test.

I ran the BIOS testing and “Hard Drive 2” gives me an error, but even if one of the aux hdd’s is failing it should freeze the OS, the OS isn’t on it.

"Error Code 0146.
Msg: Error Code 2000-0146
Msg: Hard Drive 2 - Self test log contains previous error(s) The given error code and message can be used by Dell Tech Support to help diagnose the problem" 

The rest of the BIOS testing including the memory comes back all “Passed.” I ran error checking on the drive in question, and it came back with nothing. I unplugged that drive, and the system still freezes.

 The only thing I haven’t switched out, besides the processor, is the RAM. I have 8 GB of RAM and it passed all the testing, so I didn’t think about physically reseating it or removing a stick at a time and testing.

 When I removed the old PSU I had to move a fan by the processor, I vacuumed all the dust out and verified it was working, as well as the other fans, so I don’t think the CPU is overheating or anything.

 I’m at a loss. I don’t know what it could be. My PC is a few years old, but it’s still decent for what I use it for, I don’t play any games or anything, so I don’t want to just trash it!!