I have yet to see a quality psu that comes with enough PCIE connectots, its annnoying.

Unfortunately I can't get you hard numbers on a 6870 as my current set up with one won't allow me to underclock the mem, however 150 - 175W from the wall is probably a reasonable estimate, unless you go really crazy with overclocking, so 175*4 = 700W probable max draw from the wall. A 750Watt PSU would be a very safe buy for a normal system (dont go supwe oc'ong a high end cpu though), you could probably get away with a 650Watt PSU, but most people seem very skittish of taxing their PSUs for some reason, go figure.

The COrsair AX750 is probably the best PSU out there, but also probably overkill for your needs, but if you want the best, that's something to look at. The FSP Aurum gold 700W is a decent PSU and should be able to handle your needs while giving you Gold Efficiency at a decent sticker value. LEPA G700-MA is also in the decent category, and it's cheap with a MIR right now from the egg. Thermaltake Toughpower Grand GOld 750 also good and going for cheap.

Those are just some of what's out there, but they're all quality units with good warranties in case you get the rare defective unit and they're not bank breaking (I recommend gold rated PSUs for anyone running a 24/7 high load rig, as it will actually pay off the price difference in a reasonable period of time).