PSU should handle it (unless you have an ElCheapo, or one that came with the case). I'd recommend an aftermarket heatsink for your CPU (if you are still using the stock one). Then OC a bit. Good PSU brands: Antec, Corsair, PC Power & Cooling, Silverstone, or Enermax. Here are some ideas for new HSF's (others may have more ideas).
OC'ing the processor will only help FPS if it is the bottleneck. A stock i7-9xx is not going to be bottlenecked by most/any card on the market right now... maybe with SLI or Crossfire that could be a concern.
The stock processor speed may limit your gaming, but it will be due to calculating parameters outside of the graphics (A.I. movement decisions, etc.).
Just wondering, will my current 500W power supply will be able to handle this or not?
A Radeon HD 6970 has a maximum board power of 250 Watts. That means this graphics card itself will draw up to a maximum of 20.8 Amps from the +12 Volt rails (This could happen if you run FurMark). Typical gaming will draw up to 16 Amps. AMD recommends a power supply with 550 Watts or greater with a minimum combined +12 Volt current rating of 42 Amps and at least one 8-pin PCI Express supplementary power connector and one 6-pin PCI Express supplementary power connector.
If your 500 Watt power supply has a combined +12 Volt current rating of 42 Amps or more with at least one 8-pin PCI Express supplementary power connector and one 6-pin PCI Express supplementary power connector then it will handle the Radeon HD 6970.
If your 500 Watt power supply's +12 Volt current rating is below 42 Amps you may start to run into problems when other devices (e.g. CPU, Hard Disk Drives, Optical Drives, etc.) that depend on +12 Volt power will be starved of power or the power supply's over current and/or over power protection circuits (i.e. assuming your power supply unit has this) will be triggered shutting down the power supply.
Also, cheers for all the replies. This probably wont be happening till October time anyway (BF3 ), but in terms of power/price the 6970 does look good (unless you guys have other suggestions?). Hopefully it'l be even cheaper by then anyway.