I thought I'd fixed my data integrity issues by replacing the motherboard, but maybe not. Tonight I'm getting errors when I copy large files from one disk to another. Memtest x86 ran for 12 hours with no errors.

(Update - not sure this is really helpful - pretty sure it's my PC, though not 100% sure which part - CPU, cable, PSU). Can a few people please try this for me. Download Teracopy, change preferences to "always verify". Copy 100GB of files (eg movies) from one disk to another. If you can try between two spinning disks and between a spinning disk and an SSD that'd be interesting. If you hit "more" during the copy the tool will report any CRC failures. I'd like to know if anyone else gets any CRC errors at all. Today I got 5 errors copying 100GB of movies around, and copying one 100GB file just won't succeed without errors.

Motherboard is new, memtest passes every time never an error, the Intel processor test passes every time, Prime95 passes every time, and it happens with each of my 5 disks. I've changed some cables since I last tested too.

The main thing I'm wondering is do these CRC errors happen to people regularly and they just don't notice because it's never checked, or is there something wrong with my PC? I hope it's just my PC, that I can replace quite easily. I just don't want to spend $1500 replacing it and then find the new one does the same thing.

Update - SOLVED! It was the RAM. See the information on page 3 for more details.