It wasn't even that, I tried the cards one at a time and they didn't work I have now updated the BIOS, and checked my BIOS settings, I have also got rid of a few Asus utilities. The next step after that lot (The cards havent arrived yet) will be to try a full format - which is a pain as everyone knows - and load stuff up step by step.
oic, but it was definitely the first red slot you were using? if you try to use one of the nf200 slots without the cpu pci-e lanes (1&3) populated it doesn't detect anything (nf200 not engaged). Or at least that's what it's like for me.