Black screen crashes on 2 computers, one mobo died

I've been having random black screen crashes on my desktop for weeks now, and the mobo finally died. I've been using an old laptop as a replacement but noticed it is now having the same issue. I'm afraid that when my replacement motherboard arrives, it's going to die as well. I've tried everything to diagnose the problem and have ran out of ideas.
Updated info:
Current original PSU: RAIDMAX HYBRID 2 RX-730SS 730W ATX12V V2.2/ EPS12V SLI Ready CrossFire Ready Modular Power Supply, New Version with Build-in LED Fan On/Off Switch
New replacement PSU I tested with: Rosewill RP600V2-S-SL 600W ATX12V v2.01 SLI Ready Power Supply
UPS: CyberPower CP350SLG 350 VA 255 w 6 Outlets UPS

Ok, here's more detailed info from my previous post on reddit:
I built my desktop around 3 years ago and have had no problems till recently. It will randomly black screen and sometimes reboot, sometimes hang on the black screen till I hard reset. I thought it was the PSU after testing the ram and updating all drivers. I even reflashed the BIOS to no avail. After replacing the PSU and still having the crashes, I thought dirty power could be to blame, so I bought a UPS and still have the same issue. Oh, and the part that really stumps me, is that my laptop is having the same issue, thus why I suspected dirty power. If anyone has any ideas, I would appreciate the input.
Hardware specs (Desktop): Microsoft Windows 7 Home Premium 64-bit SP1
CPU AMD Athlon II X3 435 27 °C Rana 45nm Technology
RAM 12.0 GB Dual-Channel DDR3 @ 663MHz (9-12-12-30)
Motherboard ASRock M3A770DE (CPUSocket) 30 °C
Graphics Acer S201HL (1600x900@60Hz) ATI Radeon HD 5700 Series (ATI AIB)
Hard Drives 932GB Hitachi HDS721010CLA332 ATA Device (SATA) 32 °C
Optical Drives ASUS DRW-24B1ST c ATA Device Audio AMD High Definition Audio Device
Original MOBO that died: ASRock M3A770DE AM3 AMD 770 ATX AMD Motherboard
New MOBO (not arrived yet): MSI 970A-G43 AM3+ AMD 970 SATA 6Gb/s USB 3.0 ATX AMD Motherboard
Hardware specs (laptop):
Operating System: Microsoft Windows 7 Ultimate 64-bit
CPU AMD Turion X2 RM-72 60 °C Griffin 65nm Technology
RAM 4.00GB DDR2 @ 267MHz (6-6-6-18)
Motherboard Compal 30FC (Socket M2/S1G1) 52 °C
Graphics Generic PnP Monitor (1280x720@60Hz) Acer S201HL (1280x720@60Hz)
1918MB ATI Radeon HD 3200 Graphics (HP)
Hard Drives 298GB TOSHIBA MK3255GSX ATA Device (SATA) 32 °C
Optical Drives HL-DT-ST DVDRAM GSA-T50N ATA Device
DTSOFT Virtual CdRom Device
Audio AMD High Definition Audio Device

Update: After continued use, the desktop has gotten to the point where it will no longer post, and the laptop doesn't seem to crash at all anymore.(edit: scratch that, the laptop is still crashing...) I took the desktop to a friends house (who I built his system for him) and tested my componets. The GPU and CPU and ram all worked perfectly fine in his system, but trying his gpu, cpu, and ram in mine did not work, so I've concluded it must be the motherboard. Ordered a replacement, it should be here in a few days.
Details about the crashes: The desktop crashes are at random times from idling on the desktop, to watching a video with vlc, or browsing the web. It has also shutdown while in the bios once or twice. It has frozen screened with non-responsive mouse/keyboard 2 or 3 times (able to use the reset button), and the other dozens of times, it does a complete shutdown with the monitor saying no input, and the case fans/leds still on. (requires hard reset by flipping the PSU switch.) The laptop crashes are more frequently frozen screens, sometimes with grey lines like a video crash. I did take the desktop to another location to see if it was the power in my home, bad wiring maybe. Still had the crashes.