It varies between CPUs, but I would say around 3.2 would be a good overclock. Probably not much difference between it and a 7750. Just keep a eye on your temps. Those 65nm. heated up with voltage.
You got a BE, the only two setting you really have to change is your X and CPU voltage. The 7850s X stock is at 14 I think. Just bump it up to 14.5, reboot and see if its stable, if so try 15. When it gets unstable you can either back off or start raising your CPU voltage. Dont know what the stock voltage is on that one, but like if its 1.325 bump to 1.350. But like I said if you start raising the voltage keep a eye on your temp.
Yes the multiplier. Overclocking a CPU voids the warranty, but I wont tell them if you dont.
But its pretty simple. Just raise the X till it gets unstable, then just back it off some, if that speed is good enough. If you want to go futher you will need to bump up the voltage. Just watch the temps. when you start raising voltages.
People say from 24 hours to 2 or 3 hours. 2 to 3 hours should be fine. After that just pop in the most demanding game you have, run the hell out of it and watch the temps. and you should be fine. As long as your not getting any errors or file corruption.
What do you want to spend on one?
The one I have, but you better have a wide case, its pretty tall.
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The highest its ever been is 41c
At idle its usually around 31/33c
Yes the multiplier. Overclocking a CPU voids the warranty, but I wont tell them if you dont.
Indeed since if the CPU goes out they can't prove it ^-^
Its not bad but id go with this if it will fit your case (medium+ towers will be good)
http://www.newegg.com/Product/Product.aspx?Item=N82E16835185125&Tpk=Arctic 64
I run this on a 5400+ @ 3.4ghz the voltage currently is lost on me but it never peaks 50c.