The paste that comes with the Noctua cooler is one of the best on the market. The liquid metals are better but are hard to use and unforgiving if you mess up the application.
Edit: You won't be heat limited by that processor in any case. Even if you delid it and drop temps 20-30C it won't overclock any better.
I overclocked my cpu @ 4.7ghz with 1.15V and when i stress it with prime95 (26.6) MAX temps with all 4 cores are at 61-66C. is that good? And is it affecting my cpus longevity or something? Those temps are MAX but its jumping around 58-64C
EDIT: When i applied that OC and im at idle on desktop cpu runs @800mhz with 0.7V but my temps are 31-36C. When @stock settings at idle, my temps are 28-32C with same frequency and volts. Fans are always with stock pwm