F5F Stay Refreshed Hardware Desktop Observation of voltage reduction in USB connections

Observation of voltage reduction in USB connections

Observation of voltage reduction in USB connections

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Du_Jus_Oasis
Member
170
01-11-2023, 01:16 AM
#1
Hi, I see the USB ports on your H81M DG4 are behaving oddly. Most aren’t recognized, and the voltage readings are inconsistent—some drop to 2.75V even under minimal load, while others stay at 5V without load but fall to 4V with a small current. It looks like a hardware issue rather than a power supply problem. You mentioned looking for USB tools or Linux commands that manage drivers like SpeedFan does for PWM control. I’m not sure if such utilities exist for this specific setup, but you might try checking BIOS settings, updating the USB drivers, or using a tool like `usbtool` to inspect ports. If you want, I can guide you through basic steps to test and possibly reset the USB configuration.
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Du_Jus_Oasis
01-11-2023, 01:16 AM #1

Hi, I see the USB ports on your H81M DG4 are behaving oddly. Most aren’t recognized, and the voltage readings are inconsistent—some drop to 2.75V even under minimal load, while others stay at 5V without load but fall to 4V with a small current. It looks like a hardware issue rather than a power supply problem. You mentioned looking for USB tools or Linux commands that manage drivers like SpeedFan does for PWM control. I’m not sure if such utilities exist for this specific setup, but you might try checking BIOS settings, updating the USB drivers, or using a tool like `usbtool` to inspect ports. If you want, I can guide you through basic steps to test and possibly reset the USB configuration.

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DankNames
Member
122
01-18-2023, 01:47 PM
#2
There’s no method to regulate voltage. Certain USB connections might receive 5v standby from your power source, while others could draw directly from 5v. A MOSFET functions similarly to an on/off switch, potentially cutting off a port when excessive current flows or a short occurs—though these devices usually don’t lead to voltage drops. I’d think the power supply isn’t providing stable 5v to your components and USB ports.
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DankNames
01-18-2023, 01:47 PM #2

There’s no method to regulate voltage. Certain USB connections might receive 5v standby from your power source, while others could draw directly from 5v. A MOSFET functions similarly to an on/off switch, potentially cutting off a port when excessive current flows or a short occurs—though these devices usually don’t lead to voltage drops. I’d think the power supply isn’t providing stable 5v to your components and USB ports.

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DerpGamerPJ
Junior Member
17
01-18-2023, 09:10 PM
#3
Ripple and voltage on the 5V, both are stable and +5V to the motherboard is perfect. The ripple is minimal and not noticeable with my oscilloscope (though slightly high ripple might cause this). I switched to a different power supply just to confirm the same issues. I suspected a short circuit, but when unplugging the PSU immediately after, capacitors on the motherboard and PSU would drain, yet voltage remained stable until it began dropping like any other system. The good news is USB devices function properly even at lower voltages, ensuring data transfer continues. Short circuit detection also works without issues across all USB ports. If no software exists to fine-tune settings, I’m at a loss. I’ll attempt to disable USB ports individually by removing drivers one by one to identify the problematic port.
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DerpGamerPJ
01-18-2023, 09:10 PM #3

Ripple and voltage on the 5V, both are stable and +5V to the motherboard is perfect. The ripple is minimal and not noticeable with my oscilloscope (though slightly high ripple might cause this). I switched to a different power supply just to confirm the same issues. I suspected a short circuit, but when unplugging the PSU immediately after, capacitors on the motherboard and PSU would drain, yet voltage remained stable until it began dropping like any other system. The good news is USB devices function properly even at lower voltages, ensuring data transfer continues. Short circuit detection also works without issues across all USB ports. If no software exists to fine-tune settings, I’m at a loss. I’ll attempt to disable USB ports individually by removing drivers one by one to identify the problematic port.