Very high (and increasing) UDMA CRC Errors in SMART report

Hi,

I have recently built a new NAS with 6 new 2TB WD Red disks for zfs data, and I am using 2 older 320GB Toshiba disks for Ubuntu in Raid 1.

The OS disks are not new, but have been used a little bit in some laptops before being ripped out.

Ever since I set up SMART monitoring, I keep getting a huge number in the UDMA CRC Errors column of the report for both disks.

As of today for disk 1 and 2 read: 54068696 and 25632701 respectively, and these numbers are increasing by about 400,000 every day...

I have read online that this generally means there is some kind of cable coection issue, rather than something to do with the disks themselves.

All parts, except for the 2 320GB OS disks are brand new (will post build specs if needs be).

My mobo only has 6 SATA ports, so the OS disks are plugged into a PCI Express Sata Controller, maybe this could be the cause of the issue?

I'm just not sure. Anyone able to shed any light on this?

Thanks, Chris.