Just my 0.02 cents
My original R808 has been running 24/7 for months now @ 150mhz solid
Reading and following the advice on this board:
Replaced both fans with 50 x 50 x 20 units from Amazon
Both original fans were starting to fail, slowing and chattering but they served their time well up to this point
Original M3 screws were replace with M3 x 50mm. Heatsink was drill & tapped perfectly so replacement was easy
R808 is now running @ 175mhz comfortably
The only downside is louder fans, to be expected tho.
Also changed power supply from the 6A brick to a Corsair Gold PS and using the 6 pin connector
I know it's my imagination but the R808 seems to start faster and run better with the 6 pin connection
Overall, the R808 design was extremely well designed