I want to replace my Sempron 3400 with an Athlon 4000. I was wondering if I could use the same heat sink? Do I need to buy some thermal compound if I use the same one?
Best to buy a retail item instead of OEM as they come with the correct heatsink. You could use your existing heatsink but I wouldnt recomend it as it could cause overheating.
Retail CPU's come with the heatsink and thermal compound...
No, you can use the same heat sink, but you will have to clean off the old compound from the sink and the CPU, and apply fresh compound to the CPU.
Don't expect a noticeable performance increase, though.