Mine used to run at about 48-49C after playing for a while on the desk. I don't know what temp it settled at if I left it on standby overnight. Now I've fitted the fan it runs at about 38-40C. Sounds like yours runs a bit hotter than mine did. Have you actually checked the temp with a thermometer and compared it with Vital Signs?
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Marcus 32 gig MKII (various colours) & 30gig MKIIa