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What mobo/RAM/hsf and case cooling do you have?
Most single core AMD processors of a certain pedigree are capable of reaching up to 3Ghz. You're 4000+ SD core is a good start but the o/c is dependant on your other hardware too.
If everything you have is capable then as a rough guide:
First look for a setting in BIOS named something like HT Multiplier and set it to 4x for the purposes of this o/c. Make sure you have a copy of cpu-z installed on your pc and a utility for monitoring temps. (Refer to these after every increase on your o/c)
4000+ is 2400Mhz (200[HTT]x12[cpu multiplier]) To achieve 3000Mhz you would need to go 250x12. This would give you a faster cpu AND a faster system bus.To get to this speed though you would need a voltage increase (vcore) on the cpu. These increases are done incrementally and, on good air cooling to a maximum of 1.6v. (Preferably no higher than 1.5v). I say incrementally as you shouldn't try for a maximum o/c on the first hit. Instead you need to raise the HTT a step of 5Mhz at a time. Test for stability each time by booting to windows and running something to stress the cpu. (Try superpi to start with). When you reach a point where you cannot boot at all, or the stress test fails you can raise the voltage one notch at a time to see if it helps. (It will)
Raising the HTT will also make your RAM run faster. 250 is achievable on some RAM but not all. Again we need to know what you have. RAM can be made to run above the default speed of 200 by a couple of methods. By raising the voltage (vdimm) in the same way as you do the cpu voltage to a maximum 3.0v (as a rough guide). Some RAM reacts well to a voltage increase
like this allowing you greater speed. Another way is to relax the 'timings'. The important ones being CAS Latency, Ras To Cas (Trcd), Row Precharge (Trp), Min Ras Active Time (Tras). If your RAM is rated at 2,2,2,5, for instance, then relaxed timings may be 3,3,3,7.
If your RAM is not capable of reaching 250 using a combination of relaxed timings and voltage increase you can use a divider i.e 133, 166 etc. These are all given as a ratio of 200 i.e 3/4, 4/5, 9/10 etc. So with your HTT at 250 and using a 9/10 divider your RAM would run at 214Mhz. (If you want a detailed explanation of the maths behind this i recommend you read a more detailed o/c guide). 214Mhz is far more achievable for most makes of RAM than 250 and may be a suitable setting for you. (Again depending on what you have).
Bottom line here is a cpu o/c to 3000Mhz, HTT o/c to 250 and RAM o/c to 214Mhz (DDR428).
Once you have reached this, and tested every step of the way with superpi, it will be time to REALLY test for stability. There are several utilities for this but Prime95 is one of the most common. Personally i think there is nothing better than running a game like COD2 to really stress your system to the max, but to each their own
Remember that having a gfx card working hard inside your case will add to the heat so watch those temps!
I hope you can get a good 3000Mhz clock out of your new cpu and i wish you luck. Post some details of your hardware and let us know how you get on.