Why are some of my USB ports not working? (Appear to be running out of power)

theminislimshady

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Jul 29, 2013
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After upgrading my case (which added 2 USB 3.0 ports as well as a few fans) I noticed that some of the USB ports didnt work. It wasn't just the front ports, it was also the motherboard USB ports. My keyboard and mouse sometimes didn't light up, but they still worked. When I plugged in one USB device, others would stop working. Usually the USB 3.0 ports would cause more devices to stop working than the 2.0 ones would. I've included a screenshot of my specs, shown in a power supply calculator. This calculator says I only need a 350W power supply. Currently I have a 550W supply. The model of the supply is the LSP550 by Ultra. (The power supply is not well known, so here's a link to the page I bought it from. I couldn't find a manufacturer page but maybe I'm just bad at googling.) Anyways, I bought it around 3-4 years ago. Before the upgrade, all devices worked fine and had no power loss symptoms.

These were the changes that I made to my PC during the upgrade:

-Added 4 x 120mm LED fans
-Added 1 x 120mm non-LED fan
-Removed 1 x 80mm non-LED fan
-Kept 1 x 120mm non-LED fan that I had in my old case
-This makes a total of 6 x 120mm fans, 4 of them with LED lights and 2 without LED lights
-Added an SSD (Samsung 850 Evo 500GB)
-Removed a hard drive (7200 RPM, SATA-II, 500GB) (Replaced by SSD)
-Removed a DVD Drive (can't remember exactly what model but I think it was a DVD-RW drive that I kept from my old Dell Inspiron 530 from around 2008)
-Reinstalled Windows 10 64-bit (for the new SSD)
-Installed all drivers

Another thing to keep in mind is that 4 of my fans are connected in a chain of 4-pin molex connectors, the 5th one has it's own 4-pin molex, and the last one is connected to the motherboard's fan controller (I only have a single fan controller on my board).

Finally, here is a link to my specs, and a power supply calculator showing the estimated power usage which my power supply exceeds by 200W.

So what is causing these issues? According to the calculators, I should have more than enough power. Sorry for the super long, confusing, and complicated post, but I wanted to give as many details as possible.

Any help is appreciated! Thanks! :)
 

rgd1101

Don't
Moderator


missing the mobo make and model
 
Quick check:
I see you added front USB that you didn't have before. That's the main difference, unless something died when swapping things out. So:
a) shut down PC
b) Unhook front USB connectors from motherboard

More info:

1) USB uses the 5Volt output from your computer, and the fans via MOLEX etc use 12Volts so it's unlikely there's a direct issue there.

2) It might be a defective power supply, but the only way to be certain is to SWAP it out or find what the problem is another way.

3) My testing advice is to UNHOOK everything you absolutely don't need such as:
a) All fans except the CPU fan
b) all SSD/HDD's, DVD drive
c) Graphics card (if you have onboard graphics you can use).

Now that you have the minimal configuration, use ONLY your keyboard and see if it works fine to enter the BIOS. If no issues start adding things back.

If you have issues in a reduced state then it's probably your:
a) motherboard, or
b) power supply

Other:
Sometimes people have GROUND OUT the USB connection somehow.
 

theminislimshady

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Jul 29, 2013
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My mistake. Motherboard is a Gigabyte GA-78LMT-USB3 Revision 5.0.
 

theminislimshady

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I knew i was forgetting something! To clarify, I already had 2 front USB ports. However, the 2 ports on the old case were USB 2.0 and the 2 ports on the new one were USB 3.0.