Core Voltage and I/O Voltage

[Twinhead]

What is the difference between this two voltage? I've overclocked my Athlon Classic from 750MHz to 900MHz with perfect stability using Abit KA7-100 motherboard, and just changed the core voltage. I've planned to move further also, to 950MHz, but unsuccessful. If I change the I/O voltage as well, will it go to 950MHz or more? Thanks.

 

[H4rm]

I have the same questions, plus what side effects (harmful ones) can result from altering the I/O voltage and core voltage?
1ghz @1.2 ghz 34 deg C. alpha Pal6035 and 38 cfm (AIR COOLED ONLY)

 

[Outlaw]

I/O voltage is the voltage to the Video cards through agp and PCI.
MAny GeForce cards needed 3.5v as apposed to the 3.3v default under most bios settings.
The I/O voltage also effects ram and all the other PCI cards though.

Many bios updates now set the I/O voltage to 3.5 @ default now.

I would not worry about this effecting the CPU core voltage @ all.

I would not set any voltage above spec unless it is supercooled with water and peltiers.

If you do have supercooling available and you want to reach higher speeds these voltage tweaks are great. We had a C366 and a TnT-1 that we ran with games enabled @ 735 Mhz totally stable only thanks to the voltage tweaks. The CPU votltage was like 2.9 or somthing crazy like that and I/o voltage was maxed out @ 3.9 I believe