The Set Up:\nBoard-P5LD2\nDual Core 3.0 Pentium\nStandard supplied fan and heat sink\nUsing SpeedFan 4.27 to monitor\n\nThe Situation:\nFor 3 hours have been running stable and SpeedFan reports the CPU fan\nspeed at 2600 when at 100%. When the CPU temp drops below the set level, it\ncuts the fan back. Fan speed picks up when the processor is loaded and the\ntemp goes up. Works as advertised. So far-so good.\nBut........this is with the case side off.\nI put the case side on...now....\n\nWithin 10 minutes, STILL showing as 100%, the CPU fan will ramp up to a\nscreaming 3600 rpm!\nNo load on the CPU.\nCPU temp the SAME or cooler.\nCase temp the same.\nHard drive temps the same.\nIf I take the side off the case, it spools back down to 2600 rpm within 10\nminutes.\n\nThe Question:\nSo why now is 100%=3600 rpm, when 10 mins. ago-\-\-\-with all the temperature\nparameters the same-\-\-100%= 2600 rpm?\nBefore, with the case side off, I could load the CPU up, run the temp up to\n55 or 60 degrees and it still sat at 2600 rpm. Now, with the side on AND at\nthe cooler temps-\-47°-48°-\-, it's running at 3600 rpm. And even if I disable\nSpeedFan so that the MOBO runs it at 100%, it's still continues to run at\n3600 rpm.\n\nMid tower case.\n1 small input fan blowing across the drives.\n1 small output fan in the back, with a duct positioning it right next to the\nCPU\n2 fans in the power supply pulling air out\n\n\nAnybody got any ideas?\nAnybody know what the max speed of the Intel supplied fan is supposed to be?\nIs something going on with air pressures inside the case? But even so, if\nthe temps are holding, why the speed increase? And why is a reported 100%\ntwo different speeds?\n\n\nThanks all\n\n\nT.O.