I recently built a computer around the intel i5 2500k, with Asus p8p67 mobo. One of the dimm slots was defective so I replaced it. However, now I face a dilemma: When I built the PC i didn't use any thermal paste because that is what the processor manual said so. Now that I took it apart (after about 2 weeks of use) there is a gray glue-like substance on both the processor and the fan which I imagine is the equivalent "thermal paste" is came with. My question is, now that I got my new mobo and am about to rebuild the pc, should I just put it back together as it is, hoping that that "gray paste" will melt and still do its job, or should I wipe it clean and buy some new thermal paste? I don't really do any overclocking.
If I need to buy new thermal paste, how should I clean that gray substance off the processor and fan? and what is a good paste to buy?
While if the previous thermal paste is still soft, you should be able to re-use it, it is not recommended as it will likely not give ideal surface contact, it is a good idea to put some fresh compound on, especially since it only costs a few dollars.
Fingernail polish remover also works well for removing old paste (or adhesive thermal tape). Just remember to wipe the surface down with alchohol before applying new paste (both the HSF, and CPU). AS5 (I use either Noctua, or Ceramique) is the standard, and runs between $.99 and $10 (depending on tube size). Place a dot (the size of a small pea, or grain of rice) on the CPU then either: Attach the HSF, hoping the pressure spreads the TIM, or get a latex glove and spread it around a bit before attaching the HSF.