гугль же
"Well, it depends if it is a C64 breadbox (old board) or a C64-C (new board).
A old board C64 will stay drak when 9V is missing, a new board one will display a start screen but will not work 100%.
Me too thinks the Ram problems are because of the ATX psu supplying not enough current or a wrong voltage, they are built for higher loads than a C64 will draw, and do not work or not work correctly if there is no or not enough load.
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