Video Card Overclocking Guides?

[erorr404]

i cant find an in-depth VGA overclocking guide anywhere. does anyone know of any good ones, or if not, can perhaps just answer some of the following questions?

1. how exactly do you find the limit of your Core or Memory clock? is it practical to keep one at default frequency while overclocking the other until artifacts or stability issues arise?
2. is it best to maintain a specific ratio between Core and Memory clocks (ie, if stock speed is 500 core/1000 mem, do you have to keep a 1:2 ratio between them)? or are they totally independant?
3. how do you increase the voltage of your video card? is it the AGP/PCI ratio in BIOS, or is that something different?
4. what are some physical mods that you can do, and what do they do? ive heard the terms volt mod, pencil mod, etc, but have no idea how to do them or what they're for.

it would be very helpful. thanks. :)

[Daveb2012]

good post I would like to see one of these as well..

[Squid_Spit]

1. Yes to find limit, oc one to the max while leaving the other at stock.
2. Totally independent, i havent heard the need for keeping at a specific ratio
3. By doing a vmod, via software (bios flash) or a hard mod
4. By vmoding the card it allows you to increase the cores/memorys voltage thus a higher oc.

[KoolDrew]

Theres one @ EOCF in the video section.

[erorr404]

thanks for the quick answers, Squid_Spit.
and the EOCF guide seems very extensive, just what i was looking for.

however i have a question about RivaTuner. it doesnt let me raise my core or memory clock past a certain point, saying that the drivers dont support it or something like that when i press Test. im sure this is normal, but i think my memory clock can go past their limit while still being stable. their limit for my core is around 600 MHz, and it i get artifacting starting from around 580 MHz, so thats fine. but they limit the memoery speed at around 1175 MHz, and i seem to get perfectly stable, artifact-less results at that frequency. so in short, i think my cards memory clock can go higher but RivaTuner does not allow it.
is there a way i can get around this, or should i trust RivaTuner when it says its unsafe?

thanks.

EDIT: btw my card is an AGP XFX 6600GT 128MB, default core/mem = 500/1000.