I have one “bad” Antminer U1. Well… bad… at stock Freq it runs fine, when I tune it to 0981 it has about 30% hardware errors. Time for some research and tune up. I took off the cooling plate with the antminer logo. There is no cooling pasta between the plate and the PCB but some kind grey rubber something. Must be conducting too I guess but threw it away. First I wanted to fit a huge CPU cooler from an old Dell PC but it’s a little overkill. I had an alumium heatsink, cut a bit off with a saw. Drilled two holes in it for the screws. Applied some thermal paste, fitted the heatsink and tightened the screw. Applied the Antminer cooling plate just for the looks.