OK guys this is frustrating me so I thought I'd throw it out to the forum for some other things to check.
After many many years with PCs I decided to build my first custom water loop PC.
Main parts list consists of
2x Gigabyte G1 gaming 980ti - EKWB WF3 GPU block + back plate.
Rampage Gene III + x5670 (Xeon / LGA1366)
EVGA 1000W PSU
Currently I've got everything up and running but the PC won't post with PCIE power attached, but will post with no external power (with the normal no power connected warning), or I've also found only either 1 only plugged in .
Stripped down one of the cards and nothing changes, tried either with no backplate no difference, each card individually also.
No noticeable damage to either card, everything worked on air prior.
Hoping I've missed something simple...