Noisy ethernet cables

You probably want to stick with shielded Ethernet, regardless of the Cat #

I mis-posted, the newest one is Nordost Blue Heaven. It's noisy too!

Ethernet over UTP offers galvanic isolation from transformer coupling. Any noise you are noticing must therefore be from EMI/RFI picked up by the cable. The fact that multiple cables exhibit noise confirms this.

I would try to locate sources of interference.