Which cooler is better and by how much?

which one is better and by how much? Im using athlon x2 3800+ am2 EE

Arctic Freezer 64 Pro

http://www.arctic-cooling.com/cpu2 [...] x=80&disc=

or

Titan siberia

http://www.titan-cd.com/eng/cpu/siberia.htm

ps. can better cooling substitute for voltage increase when ocing?

have you increased the voltage or just keeping at 1.25v? however the zalman is more expensive

The Arctic Freezer is a popular well-reviewed model, and many here have given positive feedback.

I don't know much about the Titan Siberia. A review here http://www.techniz.co.uk/modules.p [...] 155&page=7 is generally positive, but their method of testing is not so accurate, and I don't know which model of stock AMD cooler they compared with (AMD used to bundle weaker HSFs than they do now).

Can better cooling substitute for voltage increase when ocing?

Sometimes yes, sometimes no. Most people get better cooling to reach a higher maximum overclock with a higher required voltage. The x2 3800+ EE is a cool-running chip, and it's manufactured using SOI, which isn't so thermally bound. I'd say the odds are that you won't be able to reduce the voltage simply because of better air cooling. But you could run stably at a higher voltage, which means higher clocks, up to a point.

Let me get this straight!

You have the EE version of an AM2 x2 3800+.

and

You want to use after market cooling to OC.

mmmmmmK.

Given the 65W used by this chip the stock cooler should really be all you need.

Just think an aftermarket cooler may be overkill right now.

You should try the OC with your stock cooler and see where you get to, with dual prime95 stable.

I think you might be suprised.

Were you thinking of trying an extreme OC?

For the choice between t hose coolers, I'd say AF64PRO all the way. It's effective, reliable and moderately quiet; don't get Titan sh!t.
On the other hand, a X2 3800+ EE that is unstable @ 2.2GHz is pretty odd; you're either very unlucky with it or you're not OC-ing it properly (you have't adjusted the memory timings properly, haven't dropped the HTT multi from 5X to 4X, have a really bad airflow in your case or something like this).
That chip will be fine even with 1.35-1.40V until you keep it under 55°C. I would advice you go get RMClock; it overrides AMD's driver and allows you to play with Voltage and frequency IDs so you can have your customized power scheme. It will allow you to go up to 1.40V while letting you keep an eye on the temps, reading them directly from the on-die diode.