SOLVED Overclocking iGPU

Hi,
I have an ASUS P7H55-M motherboard with an i3 530 CPU. Since I'm not a gamer, and owing to budget issues, I've opted to live (for sometime) without a dedicated graphics card.
But, I recently came to know that the iGPU can be overclocked, to a certain degree, to enhance the HD graphics experience.
I have overclocked my i3 to a stable 4Ghz, running at a core of 1.224v
Any help on iGPU overclocking would be great.

There should be some bios options to raise the igpu frequency... like any overclocking, raise it until its freezes or in the case of videocards (igpu too) until it artifacts.

Thanks for the response Earthdog,
Yes, my P7H55-M does have a few options on iGPU, I think.
1) Something like iGPU / BCLK sync mode (sorry at work) Enabled/Disabled
2) iGPU frequency, in Mhz

But, if I increase the frequency here, where should I increase the voltage, or which parameter provides the iGPU with voltage?

Anybody who's done this overclocking with this board?

There's another parameter like
Initiate Graphic Adapter - options are PCI/PCIe, PCIe/PCI, iGPU, iGPU/PCI, iGPU/PCIe and a few others.
Manual says this parameter allows me to select the graphics controller as the primary boot device.
So, I guess, in my case, this should be selected to 'iGPU', as I do not have dedicated graphics card, right?

Yep!

I dont know if you can increase the voltage on the igpu or what voltage does that, sorry.