Nope I don't. Since some other guys have the same problems now... And I triple-checked the PWM freezer, it does not touch anything except the PWMs.
And I don't think it's the PSU, not anymore. Not since my friend with the oscilloscope tested it and told me that it's perfectly fine, no ripple or spikes or whatever.
I think it's just >100A for a continuous period of time = goodbye PWMs, simple as that.

However, the guy that's developing these Mips freezers just sent a new prototype my way. This prototype is designed to use with thermal grease, not a pad. So maybe if I can keep the PWMs cooler with this prototype's help, the mobo won't die - I'll post some pics and let you know how it goes.
I am so not gonna step down from my OC because of a stupid mobo...