Found out why one of my units was not hashing and having X's on the chips. Paste was everywhere on the inside. Even the screws holding the heat sink on had thermal paste on them.
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Messy paste wont effect anything but poor cooling, unless your units are overheating, that's not the problem
His look far better than mine did... lol. I had paste on the chips, on the pcb, on the connectors... everywhere.