http://www.ebay.co.uk/itm/LPM16-25-Linkworld-LPM16-25-/400473489172 was the 7th page and finally I see a +12V rail at 9 Amperes.

Your links are mostly broken so if you want fast help, make good posts.

OK, that's pretty light for the rail that your GPUs tend to tax. Also the efficiency is a paltry 75% so all signs are pointing so far at the PSU.
http://www.tomshardware.com/reviews/radeon-hd-5770,2446-15.html confirms you could easily overtax that or another rail so you'll want to at least double the amperes on that rail.
Bob