Thanks, I'm not very knowledgeable on these things so if anything it was definitely worth posting as I'm learning a lot. I honestly thought if the psu wattage was high enough it would be able to run most gpu's.
Its funny as it makes the supply look much more capable than it is. More expensive supplies will be single or dual rail (many recent dual rail supplies have a single rail mode) and supply all their amps on a single rail. Your one is not like that at all, wattage means very little, the way it is delivered is what is important.