I thought the AX1200 and 1200i would have been the same, but clearly they aren't. My original intention was to see if someone had specific experience with the situation, rather than purely finding things on the internet.
I checked and i do have AX1200i cables, which say they are for use on TX, HX and AXi PSU's only. More complications. Doesn't matter anymore anyway as my friend is just going to replace his PSU with a new one.
Thanks to all for replying and helping out.