Need help with diagnosis!

I've just become a statistic! On friday evening i purchased the parts for a new rig, I will outline below.

Intel Core 2 Duo E8400 3 GHz, 45nm
4GB OCZ Platinum DDR2 800 (4x1024)
Asus P5Q-E Socket 775 Intel P45 + ICH10R
Dual 7200RPM Seagate Barracudas (in RAID0)
EVGA Geforce 8800GT

Initially, windows installed with no problems (I have built a slipstreamed copy with the ICH10R drivers included so it can detect the raid0 config). Once windows was installed, all drivers installed with no trouble. At this point I went out to my network file share and began copying over my photos, movies etc. This was where the horror began. Every single file I copied from the network had CRC errors, photos were showing abberations etc.

So, I think it's the RAM.
memtest86 runs for 10 hours with no problems at all.

So, I think processor.
I ran Prime for 3 hours with no failure on the setting that uses the medium amount of ram (128mb). No errors, interestingly if I run it on the setting that uses the most ram (1792MB i believe) it crashes instantly.

I think harddrive. So I swap in a known working good sata2 drive from my old rig. Same problem with CRC errors after file copies from network and sometimes even with large downloads from the web.

So I think motherboard. I exchange for a new one of same type. The problem is still occurring. While I was at it, I exchanged my EVGA video card for a better one, on a whim, Zotac GeForce 9800GTX 512MB.

So, now I have a PC that boots fine, runs every burn in test I can think of seemingly fine(Except for the odd prime max memory test), but corrupts files that I copy from the network. I'd assume it was a problem with the router, but my other computer does not show the same problem. Just for kicks I plugged in a ieee1394 connection instead of ethernet and performed the same tests and the problem still occurs.

Could I have a bad CPU? Or perhaps a bad L1/L2 cache? Heat wise, the processor is running between 25-28 idle, 35-42 under heavy load. No BSODs, no crashes.

Can anyone offer me a next step? I don't have another intel 775 processor to test with unfortunately.

Thanks & Regards,
Chris

Ok I may have missed it.. But have you tried it in vice versa. And then see if you get the errors on the other computer.

If you're still getting CRC errors after swapping hard drives and going from RAID to non-raid, it's a SATA cable or controller issue.

You could try non-raid SATA drivers and see if that's it.

What's the system log say?

If swapping to a known good drive does not work, and you're sure both your network and sata cables and connections are okay, then it's looking like the mainboard. You could run read/write diagnostics, which should fail in that case.

SATA cables/controller: I've swapped motherboards, which included the cabling, so I don't think I've managed to get 4 bad SATA cables.

RAM: I'm wondering about this myself.. memtest86+ showed the RAM was fine, but Prime failed when set to use max memory.

The only part I haven't swapped at this point is the CPU, but it's just hard to believe I got a bad one, and that it's only corrupting large files when transferred over the network....

I'll see if stepping down to 2GB of ram has any effect on the problem this evening when I get home.

Medic.. thanks, I'll give that a shot too.