hmmm, i was wondering the same thing too. That is my planned upgrade for next year. Theoretically you should be able to. Not sure if there is enough connectors on the powersupply, you can always use a splitter 6 pin to 8 pin or 6 to 6 y connectors. Some will say you'll need a new PS but others say the 750 should be enough as long as it can provide enough amps.
Anyone know how many amps to ps provides?
You should be able to run dual gtx 260 cards because according to the specifications on Newegg.com. It recommends you have a PSU with 680 watts and 40 amps on the 12v rails to run those in sli. Your psu can push 732 watts through the 12v rails which means you have more than enough and you have 72 amps on the 12v rails so you should be good to go. The psu that comes with the 630i is made to handle sli cards. I myself am getting a gtx 260 but I'm not going to run sli because of possible heat issues and some older games are not optimized for sli which means they might run worse with sli enabled. Good luck and happy gaming.
I ran dual GTX 260 OC in SLI in my XPS 630i without any power issues at all, and was able to ramp the GPU fans up to 60% using the nvidia Control Panel. It really gave my gaming a significant boost in the 630i, graphics were great. I have never tried the 4870X2 in my 630, once I had the 260's in SLI is just sat back fat and happy.
In my 630i the additional power had to come from cabbaging on to the molex power into the 6pin adapters, but that was not an issue, but I did have to purchase those because only one came in the retail box.
You should not have any problems. I did upgrade the 630i from the E8400 processor to the Q9650 at the same time, which made a dynamic duo and a kicking processor. I ejoy gaming on my 630i.
Keep me posted as to your build,