Thanks for all your help:

My virtual memory is already set to 50000 so thats not the issue.

I have ordered some molex powered risers to see if potentially thats the issue.

I have tried using a linux based OS but still get shit combined hashrates.

I am running the cards at stock settings so its not that

I am using a corsiar hx1200 powersupply, i have flicked it to single rail and will report the results. The other information is a bit confusing as i dont know how to manually assign things to specific rails in my psu.

I have tried some testing and it seems my rig just will not go above roughly 750 m/s if i plug 2 cards in, first one will hash at 450 and then next at 300, then if i plug all 4 in they will do some some random arrangement of hash rates to equal roughly 750. Has anyone ever heard of a problem like this?