"...With two 4850s paired up in CrossFire, we once again ran into issues with our power supply. Our 1000W OCZ EliteXStream wasn't always enough for the dual-GPU setup and in Call of Duty 4 our system rebooted in the middle of our test at 2560 x 1600. Thankfully OCZ sent us a PC Power & Cooling Turbo Cool 1200W unit that is certified for use with GeForce GTX 280 SLI, and if it works on that beast, it had better work with a pair of 4850s in CrossFire.
The PCP&C unit is quite loud as we mentioned in our review, but it got the job done, we were able to run all of our benchmarks without a hiccup after swapping power supplies. Despite AMD's small-GPU strategy, power consumption on multi-GPU configurations is still just as much of a problem as it is for NVIDIA...."
If 4850s can't be handled with a 1000W PSU, I'm afraid that my 750W PC Power & Cooling PSU I'm looking at will have some serious troubles handling two HD 4870s in Crossfire configuration. I figure that if 750 watts won't be enough to power them, I could probably bump my system up to a Corsair 1000W modular power supply, but that would also cost me an extra $75. Hmm... A dilemma. I know PC P&C make some seriously nice PSUs, but is their 750W Silencer enough for two HD 4870s along with likely a Q9450, a few hard drives, and other miscellaneous components?