Hey so I have a quick question concerning this combo here: http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...
That's the 650W XFX PSU and it apparently has 52A available on one rail. Is this amperage sufficient to have 2 5870's in CrossFire? Or would I need substantially more amps on one or multiple rails like the Antec 750W?
You need at least a good quality 750-850 watt unit perferbly Antec or Corsair. XFX are ok power supplies but for what they cost you can get much better for your money, but that 650 watt unit is not enough to crossfire two 5870's.
I recommend you to go for the ANTEC TruePower New Blue 750W, altough the THERMALTAKE ThoughPower XT 775W is an excellent option too. The model from Antec is a bit cheaper, has longer cables and better power mosfets in the in the active PFC and switching section. On the other hand, the unit from Thermaltake presents a bit higher efficiency and wattage and less cables attached to the PSU (better modularity).