On Mon, 03 Jun 2019 15:21:08 +0000, T. Ment wrote:

My legacy ECS K7S5A motherboard BIOS hardware monitor says the 5v is
low. So I used a multimeter to check a USB 5v header pin, and it says
4.75v.

The power supply 5v disk connector has exactly 5v, so the power supply
is good.

If I replace the 5v AGP card with a 3.3v card, the USB pin measures
4.85v. So the 5v video card causes a 0.1v drop on the motherboard 5v.

Is 4.75v PCI/USB safe? Should I replace the AGP video card to get the
extra 0.1v? I hear that 5% tolerance is OK, but 4.75v is right at the
edge of 5%.

The motherboard seems to work OK, but I wonder if it's safe.

Replace the power supply. The 5v disk connector may well come from
another regulator. At the very least measure the 5v at the motherboard
multiconector from the psu.

--
Regards - Rodney Pont
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