I am sure google could help out, but I like to hear from my fellow AMD community members.
I'll say...at least once per CPU change
I re-paste about once every year I reckon...usually as part of my water-cooling loop maintenance. I use PK1 and it looks the same more or less even after that amount of time...so could undoubtedly get away with way longer. I'm into my overclocking too so maybe it makes sense to keep things optimal? at least, that's what I tell myself.
However, it may depend on the paste. I once used some Gelid Extreme on a GPU...which went on quite "wet"...but temps were no longer all that, after six months and I decided to remove the cooler and it looked awfully dry! Bad batch...who knows...I haven't used it since.
I think the stiffer oilier pastes probably last a long time with little or no change...
I replaced the paste on my parents PC after five years and it looked OK...light use, home pc.
I guess just go with gut feeling...or with any suspicion that temps have increased. Maybe re-paste after six months first time and see if your paste of choice is looking OK..if it is leave it a year etc.
Depends on the TDP of the processor, heatsink you're using, and if you're overclocking. At least that's the way I've always looked at it. My old Brisbane Athlon x2 4850e that I use in my media server is a 45 watt chip with the heatsink from a Phenom II x4 cooling it. It runs 24/7 and I don't think I've changed the thermal paste in 3 years, but I'll reboot it every once in a while and check temps. They're fine.
If you're overclocking like arnesaknussemm then I'd say you'd want to check it yearly at the absolute minimum, and I know many enthusiasts will actually apply new TIM every 6 months. Just depends on your usage really. One thing to think about is if you're always in there messing with the heatsink and processor the more likely you'll encounter an 'accident' (bumping the memory, dropping something onto the mobo, somehow damaging the chip) In most cases I'd just monitor your temps and leave well enough alone
Only if I need to change the cooler, MB or CPU so basically never just for the pursuance of chaining the paste. I would probably do it after 4-5 years.
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