Re: Computer turns on and then just dies

s|b <[email protected]> wrote:

> On Thu, 21 Nov 2024 16:19:46 +0100, s|b wrote:
> 
>> I checked all cables and they should be fine. What could be causing this
>> and how to solve?
> 
> Forget to mention: I connected a little speaker to the motherboard and
> when I (try to) boot it beeps once, indicating the motherboard should be
> OK. There's a MemOK! switch that shows a red light, but only for a
> moment.

The single beep on cold boot is notifying the video BIOS loaded.  Before
the mobo BIOS can load, the video BIOS has to load (so you can see the
POST screen, BIOS settings, and the OS loading).

Without knowing the brand and model of motherboard, not sure what a
MemOK LED might indicate.  In general, a red MemOK LED means there is a
memory problem.  Were you inside the case touching stuff without being
properly grounded?  Because of thermal expansion and contraction when
components heat up and cool, components can "walk" out of their
connectors, or connectors can separate.  Unplug and reseat the DIMM
memory modules, and make sure they are fully seated.  Did you change the
position (slots) of any DIMM modules?  They may only work when paired in
the correct slots.  If all slots are filled, then position is not an
issue.  You might also want to unplug and replug the power connectors
(to mobo, to video card, to drives, etc) to wipe their contacts of any
oxides, and ensure they are fully seated.  You might even want to remove
and reseat any daughtercards (those in mobo slots).

If you are overclocking, DON'T.  Reset the BIOS (short the 2-pin mobo
header) to ensure you are using standard settings.  If the MemOK LED is
also a switch, I believe you can press that switch to load the BIOS
default settings.  However, some mobos come preset for overclocking
usually so they can sell at a higher price.  You might see a spec saying
"DDR4 3400*/3333*/3200*/3100*/3000*/2933*/2800*/2666*/2600*/2400*/2133"
for your mobo and what DIMM speeds it supports, but the asterisked ones
are overclocked settings, so resetting BIOS could have you using the
standard/slow speed, and you'd have to test which of the higher settings
are stable.

Don't try to boot with the old HDD installed into the computer.  Leave
out the old HDD, and boot with no drive installed.  The computer should
still boot, you get a beep saying the video BIOS loaded okay, the fans
all spin, but there will be a message on the screen saying something
like "boot device not found".  Getting that far means the system would
come up if it found an OS on one of the drives configured in BIOS.

With a red LED next to the MemOK switch, DIMMS that are incompatible or
misconfigured (wrong slots) or defective can cause a system boot
failure.  Press and hold the MemOK switch to start automatic memory
compatibility tuning which should change BIOS settings to match the
memory in the DIMM slots.  However, if the red LED lights up only
momentarily, it just might be flashing during the boot (as a test the
LEDs are working), but the system isn't getting powered off, so the LED
goes off, too.  That flash of the red LED may not indicate a memory
problem, only that the LED gets flashed as a normal event, but the
system isn't powering up.

Got a multimeter or voltmeter to check the voltages on the 20/24-pin
connector from PSU to mobo?