For the PC enthusiast installing CPUs or even modding graphic cards or memory by replacing heat-sinks, Arctic Silver 5 is a great and a must-have at $7. I can’t say that I build too many PCs these days, but if I did, I would order this in a heart beat. And here’s another review from a happy customer:
Arctic Silver 5 is the best thermal compound on the market. There are other types that might be better for specific purposes (Arctic Céramique for example), but for cooling a CPU, this is the best. I've used it extensively for quite a few computer builds as well as a few 'special projects' like replacing the thermal compound on an Asus Formula X48 mother board's Northbridge and Southbridge heatsinks. The results are always a 4-10c drop in CPU temperatures under load. You will not notice a huge difference at idle. The real gains in heat dissipation come when the CPU is being pushed. Also, don't trust the board makers proprietary software to tell you what your temperatures are; download a good program like RealTemp 2.41 or Everest for free (use google to find them). Either will give you more accurate numbers than Asus PC Probe, or whatever software your board manufacturer supplies.
HT to SetSocial.