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Bad Motherboard or CPU

PostPosted: Fri Mar 18, 2016 9:59 pm
by mntnw
I have a CPU on a motherboard, but can't determine if the motherboard or CPU is bad. The fan spins when I turn on the computer, but there's no video display. When I put the dubious CPU into another motherboard, the lights on the good computer indicate that the RAM is bad. I know the RAM is good because it works with other CPUs and motherboards. When I put the good CPU into the dubious motherboard, the CPU fan cycles on and off. Can anyone explain this unusual behavior?

Re: Bad Motherboard or CPU

PostPosted: Sat Mar 19, 2016 6:38 am
by Karlsweldt
More details about the system would help.
CPU type and speed, memory type and speed, motherboard brand and model and PSU wattage. And age of system.
On board video or video card? OS type?
Has the system worked good before, and now this problem? Or is this a new build with problems?
Standard system speed, or overclocked? Any warning beeps heard?
Is the CPU and memory compatible to the motherboard design and BIOS version?
Try one memory module in the first detected slot.. marked as "Bank 0, Slot 0" to see if you get life signs.
If an older motherboard, possibly bad capacitors. Look over all the larger ones, if any have domed tops, lean excessively or show signs of leakage, they are bad. More info about "bad caps" at http://www.badcaps.net/
If a CPU fan is controlled for need by the thermal sensors in the CPU and on the board, normal for the fan to cycle on and off, or increase in speed. And normal for the fan to spin a few seconds when powering on, then stops.

Re: Bad Motherboard or CPU

PostPosted: Mon Mar 21, 2016 5:09 am
by rascard2007
more info please......

Re: Bad Motherboard or CPU

PostPosted: Mon Mar 21, 2016 5:49 am
by Karlsweldt
Forgot to add another common cause of no life signs from a system.. the BIOS battery.
If not changed in more than 3 years, could be dead. It is only a redundant backup for when no mains power enters the PSU, to provide the +5 volt stand-by when the system is off, for the BIOS, CMOS and real-time clock. If no working real-time clock, the system may not respond.
Try changing the battery with a new one, then reset the BIOS pages as to how the system is built.

Re: Bad Motherboard or CPU

PostPosted: Tue Mar 22, 2016 8:09 am
by evasive
Please provide us with a list of:

brand/model of the motherboard
brand/model of the CPU
brand/model of the memory
brand/model of the power supply used

as things are standing now I say: incompatible stuff.
cpu/memory working in one brand/model motherboard does NOT guarantee it will work everywhere else.
so, start giving more info please so we can help you better.