Starting an overclock / Voltage Tweak

After applying the maximum voltages startup FurMark, disable full screen, select stability test, select 640x480, hit GO. This will stress the two GPUs 100%, leave it running -- your graphics card will now aslowly heat up.

Increase the core frequency, you want to monitor GPU temperatures as the GPUs can rise to 100 Degrees C now ! In Overdrive increase GPU Core clock in 25 MHz increments. After each incremental clock frequency increase, hit apply. Keep an eye out on temperatures. 100 Degrees C is your limit.

If you see artifacts either stop Furmark immediately or restart. If you system locks up, restart, repeat procedure and drop down at least 25 MHZ, preferably 50 MHz. Keep monitoring that temperature. Above 100 Degrees C is not okay at all --  the GPUs will automatically down clock if they are overheating past 100 Degrees C -- and with Furmark running for a couple of minutes, trust me .. they will.

Above an example screenshot of one of our overclock sessions -- not the final result. Don't be to afraid about a few system lockups and restarts, really. If you are afraid to do so, please don't overclock. It's not for you my man. It is needed to find the maximum threshold of what you can achieve.

Our end results:

With a little voltage tweaking the Radeon HD 5970 is very tweakable. Keep an eye on your GPU (now reaching 90 C) and VRM temps though. Bare in mind that we breached the 300W TDP now though, here's an overview of our new power consumption.

As you can see we are now 'roughly' consuming 380W with the Radeon HD 5970 due to the extra voltage used, and the higher clock frequencies. keep it in mind, overclocking increases negative risks as well as a more hefty power consumption.