I have a core i7 920, 12gb ddr3, 2x GTX 285 (SLI), 3 1TB HD, 1 lite-on recorder.
I'm currently using 850w seventeam but the psu is faulty and I'm planning on exchanging for 750w corsair, will it be enough to run my system smoothly?
While the corsair is very high quality and might handle it... GTX 285s are beasts. I would recommend you go higher.
The Corsair PSU calculator suggests 950-1000w. Its rather conservative, so I think you would be ok with the 850w model--but I wouldnt go lower.
Edit: Give yourself some wiggle room--especially if you plan to overclock anything. A stronger PSU will run more efficiently and cooler than one running near peak load.
This is on a mock system, but might offer some perspective as to just how much power you will use in relation to other setups:
...with this system it may actually be economical to get a silver/gold certified supply--you might make the money back on your electric bill. Seasonic, Antec, PC Power and Cooling, and OCZ also make some very good high-wattage power supples you could look at.