Not sure what really happened, it has to be related to the test-rig in some way as the drive was moved within minutes to the other rig and it had no idle time and diagnostics were all OK.
(could be caused by a lot of factors like, cabling, heat, OS, drivers,...)
I'll just have to keep an eye on it, it's been running as usual since I restarted the test, no MD5 errors, nothing.
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