Pavel schrieb ...
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witeresting. According to pictures it really looks like "oveclocked" CPU. Please check the frequency of clock generated by CTCM. You can tap to "CTCM_ON" solder jumper with an oscillocsope probe.
The frequency should be 66.6MHz
If the frequency is higher, you can temporarly downclock it to 1/2 by removing the yellow jumper "CTCM/2". This should allow you to boot and re-set the clock to base value.
Then please let me understand ywhat you exactly did to the system, specifically anything that could scramble CTCM config and NVRAM. That way I can possibly help.
Back to your question: 66.6MHz is the lowest base clock CTCM can be set to. If you need to go lower from whatever reason, you can disable CTMC by removing solder blob from "CTCM_ON" jumper and putting a 5V crystal oscillator in DPI8 or DIP14 packaging over it. I would suggest going a socket route too.
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... probiere mal am Nachmittag. Habe Pavel geschrieben das ich nichts an Hardware oder Software verändert hatte.