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Hotdog

How to tell if your power supply is going bad?

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Ok so I think my Power supply finally died and time to get a new one. But I noticed something that I could not overlook or rule out and thought I would get more people's input that work with computers all the time.

Recently I noticed that my PC would not recognize USB flash drives how ever it would recognize my USB hard drive that is powered externally.

My system is a HTPC setup with Q6600 CPU, ATI Radion 4870, 16gb ram and a Hauppague HDTV tuner. I have 7 hard drives and use my system as a Tivo like device with windows media center.

My power Supply is a PC power and cooling Silent 600 watt unit that has faithfully powered my system for the past 3 years. The guys at PC power and cooling told me that the power supply would have not have any problems powering what I have.

That being said today I was unable to get it to recognize my USB flash drive I figured I would power down unplug the PC and cycle the power switch a couple time to get rid of the juice in the power supply. When I plugged it back in and pressed the power button there was absolutely nothing.

I am pretty convinced it is the power supply but the point being has anyone ever noticed there USB flash drives not being recognize right before there power supply went out.

I think is just could not supply the power to the USB flash drives

Edited by Hotdog

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Ive had problems when I had too many things plugged in usb ports. The ones with external power would work while the ones that relied on usb power would not. My psu didn't fail though but was being pushed to its limits.

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Ive had problems when I had too many things plugged in usb ports. The ones with external power would work while the ones that relied on usb power would not. My psu didn't fail though but was being pushed to its limits.

Yea I forgot to mention that I have USB mouse,USB keyboard,USB printer, Charge my phone off the USB port all the time too.

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Posted (edited) · Report post

not a power supply issue imo.

flash drive failure

usb to mobo failure (from case)

mobo failure (back of case)

usb driver failure (unplugged it during read/write)

but if it was a power failure you'd know because the motherboard wouldnt post because it failed power testing or the comp wouldnt turn on.

did you try plugging the usb device into anything different? (different port, different computer)?

if it could not power your flash drive, then it wouldnt be able to power your hard drives, seeing as they use the same power source (5V rails i think it is, or 3V for usb)

what OS? xp has always had USB issues (driver related)

Edited by Sheena

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not a power supply issue imo.

flash drive failure

usb to mobo failure (from case)

mobo failure (back of case)

usb driver failure (unplugged it during read/write)

but if it was a power failure you'd know because the motherboard wouldnt post because it failed power testing or the comp wouldnt turn on.

did you try plugging the usb device into anything different? (different port, different computer)?

if it could not power your flash drive, then it wouldnt be able to power your hard drives, seeing as they use the same power source (5V rails i think it is, or 3V for usb)

what OS? xp has always had USB issues (driver related)

Windows 7 Ultimate. Tried the USB flash drive on 4 different ports and would not recognize. Tried the flash drive on another computer and they work. Three different Flash drives a 2gb , 4gb and 16gb. Computer was running just fine until I shut it off then it would not start back up.

When I plugged it back in and pressed the power button there was nothing connected to it externally. I just pushed button to make sure it powered on.

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really a weird problem (i say its weird cause ive never heard of this happening), the only real way to test it is to trial and error with a new power supply.

i cant give you a 100% answer, but i really want to say its not a power supply issue.

generally if a PSU gets a request for more power than it can output the computer BSOD's or locks/crashes because the voltage has fallen out of its set range.

depending on how the manufacture programmed the psu they could have it set to have no shutoff if it gets a request for more power than it can output, which would lead to failed peripherals. (which could apply to your situation)

wont really know until you get a new power supply as every hardware situation is different.

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USB uses the +5V rail

Do you have a toggle switch on the back of your PSU? If so, Is it toggled to "I" and not "O"?

Sounds like a driver issue and not a power/mobo issue if the external hard drive works fine. For some reason my machine has started that this last week where I have to plug my flash drive in 3 or 4 times to get it recognized. Still haven't isolated the issue but I kinda just learned to live with it.

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USB uses the +5V rail

Do you have a toggle switch on the back of your PSU? If so, Is it toggled to "I" and not "O"?

Sounds like a driver issue and not a power/mobo issue if the external hard drive works fine. For some reason my machine has started that this last week where I have to plug my flash drive in 3 or 4 times to get it recognized. Still haven't isolated the issue but I kinda just learned to live with it.

THIS. no idea why either, ive uninstalled all the usb drivers in the device manager and let it scan the computer again to install all of the usb drivers fresh, still randomly does it

win 7 ult 64 bit

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yea I have another PC with a big power supply on it but it wont fit in my HTPC case. It is a PC power and cooling 1000 watt power supply. I think I will just try it outside the case tomorrow before I buy another power supply.

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USB uses the +5V rail

Do you have a toggle switch on the back of your PSU? If so, Is it toggled to "I" and not "O"?

Sounds like a driver issue and not a power/mobo issue if the external hard drive works fine. For some reason my machine has started that this last week where I have to plug my flash drive in 3 or 4 times to get it recognized. Still haven't isolated the issue but I kinda just learned to live with it.

Some would assume that but the fact that it does not power on at all. No post at all kinda tells me that is would be the power supply. From past experience I have noticed that if it is a bad board that when you press the power button it Cpu fan will twitch just a little and stop. I am not even getting that which also points me back to the power supply. Keep in mind that I had a USB keyboard, USB mouse and USB printer that worked just fine.

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USB uses the +5V rail

Do you have a toggle switch on the back of your PSU? If so, Is it toggled to "I" and not "O"?

Sounds like a driver issue and not a power/mobo issue if the external hard drive works fine. For some reason my machine has started that this last week where I have to plug my flash drive in 3 or 4 times to get it recognized. Still haven't isolated the issue but I kinda just learned to live with it.

Some would assume that but the fact that it does not power on at all. No post at all kinda tells me that is would be the power supply. From past experience I have noticed that if it is a bad board that when you press the power button it Cpu fan will twitch just a little and stop. I am not even getting that which also points me back to the power supply. Keep in mind that I had a USB keyboard, USB mouse and USB printer that worked just fine.

Double check the I/O toggle switch on the back

If you want to see for sure if the PSU is dead, pull it completely out of the system. Plug in a fan or drive into one of the cables. Then take the 24-pin connector and a paper clip. Find the green cable on the 24-pin and stick one end of the paper clip into it and bend it around and stick the other end into any one of the black ground pins. This will jump-start the PSU. If the fan or drive powers on, the PSU is working and you'll have to start your search elsewhere (motherboard most likely if nothing will power on)

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Update.. Was not the Power supply or motherboard. Tore the system down and pulled the power supply and jumped it and it was fine. Upon inspection one of the USB pins was bent and grounding to the case and that was what was causing the issue. I removed the cable for that USB port from the motherboard and all is well now.

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