how to OC ram... voltages

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more voltage = more performance... but how much voltage is safe? i'm kind of scared of increasing the voltages to my ram because if i add to much i might kill the ram, right? and i dont know how much voltage is safe... right now i have some kingston hyperx 3200A (CH-5 chips) i have read other threads where most of you have 3.3v!

how do you safe way to add more voltage and see how much your ram can take? i would like to increase performance with out compromising the life of my computer too much.

btw i have a 3000 winchester and msi neo2 platinum with a xp-90 cooler