hmm, yes, that would be the best way i guess. however id like to avoid another order for new riser
theres no way around it, you almost have to order new risers, as ive already mentioned the molex only powered risers need more than just 12v to work, which a server psu DOES NOT provide, your still going to have to buy a 160w pico psu so why not order new risers as well, go on ebay you can find them for 30 to 40 bucks for a set of 6 pci express 6 pin powered risers, I only know this because I have some of those older risers before the 6 pin pci express powered risers came out, I use the molex ones explicitly with the atx psu, I have newer risers just for the server psu setups I also have