If I remember, the green stuff has been there years and it hasn't got any worse over time.
Next time I clean the loop I'll inspect more closely and go from there.
As for P95, it was the only application strong enough to tell me my system wasn't completely stable. The random crashing was driving me nuts and P95 pointed me in the right direct. I could run any other application test all day long.
Intel Core i9 9900K HT 5GHz
GIGABYTE Z390 Ultra
AMD ASUS STRIX OC VEGA 64
G-Skill Trident 2x8GB DDR4 4000MHz
Samsung EVO NVM.e 250GB
SeaSonic 1250W Gold
Corsair 900D + Custom Loop.