How do you know if its time to throw out mx-2?

[nightanole]

So in 2009 I guess there was a super sale or something, and i bought 5-10 1g tubes of mx-2, and just threw them everywhere. Well im still using them...

Internet knowledge would say to toss the stuff after about 3 years, and re apply every 3-4 years. Last time i used the stuff was last September, and it appears to still be working on the 3930k and the 2 xeon E5-2650's

Next up is what should i replace it with? Im down to these guys:

More mx-2 (didnt care for mx-4)
3g Noctua NT-H1
3g Gelid Solutions GC-Extreme
1g Thermal Grizzly Kryonaut

I use air cooling and around 100watt tdp processors.

 

[Nebulous]

Either of those 3 will work nicely. So long as they're not dried out, it's all good. I got tubes of MX4 and AS Ceramique I've had several years which still work fine. Got a tube of Noctua NT-H1 which is about a year old.