Overlclocking the Athlon II X4 620 (for noobs)

Overclocking AMD Athlon II X4 620.

Hi guys. I tried overclocking my FSB to 225 to get a 2.925GHz speed.

I am very much an amateur at this so I didn't change anything else. Booting up worked but after a certain number of minutes I get the disk dump booting memory blue screen error thing. I assume this is something to do with a RAM, so I used the RAM clock speed at a lower value (333mhz, it is 400mhz usually, I know it's very low). After this happened, it worked fine for a few weeks, now though every now and again I get the same errors when playing games sometimes.

Basically what I'm asking is what other settings to I need to change to keep everything else stable? At the moment I have changed back to stock speeds. I need to know what I'm supposed to do since I'm a beginner with overclocking.

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On a side question: My computer's screen has been blacking out every now and again while playing games, the sound is still there, my graphics card rarely goes above 70 degrees on full load, and even then it's not by much. Anyway these black outs have been happening on some less graphically demanding games too. I hear the Radeon HD 5750 has quite a few problems with Windows 64-bit, as I got several people with the same problem when doing a search. I have just installed the latest drivers, but not yet tested whether that has fixed the problem, which yes I know makes this kind of useless. If you know anything else I should do instead I thought I may as well tell you this problem.

Thanks a lot.