AGP Voltages? How can I tell what voltage my card is running at?

[trowand]

My mobo's BIOS has a setting that I can play with called PCI/AGP voltage. It has four options of 1.5V, 1.6V, 1.7V and 1.8V. Will manipulating this setting help with overclocking or is voltage ultimately still controlled by the graphics card? (X800XT PE). I'm having a heck of a time overclocking my new card. Also, I don't like how I had to install this new X800XT PE up to my power supply cable that is shared with the hard drive. I swear that it's robbing my HDD of precious juice that it needs to run optimally. After I installed the new card, I ran PCMark04 and my HDD score dropped a LOT. My power supply has black plugs and white plugs. Do they supply different voltages? How can I see what voltage my graphics card is running at? I know that's a lot of questions. Any help is greatly appreciated. THANKS!