About 5 or 6 months ago i decided to build myself a custom gaming rig. I have a AMD FX-6300 and radeon Sapphire HD-7850 and wondering how to overclock. I have a pretty beasty PSU (700W Gaming series) well for my setup i do anyway. 

Now i'm a complete and utter noob when it comes to overclocking. So many questions... so little time.

What does overclocking the CPU do?

What does overclocking the GPU do?

What is the best software to overclock my CPU?

What is the best software to overclock my GPU?

Is it safe to overclock either?

What is my limits to what i can overclock to?

Remember that i only want to overclock so that my gaming performance is better.Thank you to anyone whom may answer this question as I know people hate dealing with noobs.

You can oc your 7850 with sapphire trixx, on stock voltage it should do about 1000-1050 core and about 1200 with ~1,2v and 1400mem, its probably best too look for a tutorial on how to properly overclock (only raise one thing at a time, check temps, fps while benchmarking and look for artifacts etc.). For most games you could get a 30%+ boost from ocing your gpu, overclocking the cpu on the other hand only gives you benefits in a few cpu intensive or lowly threaded games, would take more time and would require you to play around with the bios. If you have a old or very low end mobo there might be problems with a cpu overclock, youd also need a good cpu cooler to get good results.

Overclocking chips should evenually lower their lifetime a bit because of higher voltages and temperatures under stress, but especially gpu are usually long obsolete before that happens (Or the solder somewhere on the board breaks, PCIe cards where never intended to have giant heatsinks and high rpm fans so that happens).

I am sorry for getting slightly of topic here, but this makes me wonder. As far as i know solder comes with a fairly large varity of different melting points. What kind is typically used for computer hardware?  

I'm not in a position to give an educated answer but I've never seen broken boards due to heat from overclocking, probably the reason why pcb cards are even used, heat doesn't transfer fully like that. From weight I concur, especially these big dual gpu cards.

I dont know the exact temp, but it melts a bit under 200c° (around 180 id guess), you can fix most broken gpus by stripping them down and baking them 5-10 mins at 200c° since the broken solder is the most likely point of failure if it didnt come with a defective component or a capacitor busted. The weight and vibration is the problem since any gpu shouldnt get over 105 c°.

Thanks for the answer, Greatly appreciated!