Question PC unable to support more than two USB devices at the same time

omgzombie

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My PC is unable to support more than two USB devices at the same time. All the ports are fine, I've tested each one of them individually and this is usually a temporary issue and gets fixed automatically after some time, ie I'll be able to use all four ports without a hiccup after some time, say an hour .Could it be an issue with the motherboard or is the SMPS to blame?
 

InvalidError

Titan
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That is some weird issue. On most platforms, USB host hubs only have two ports each, so you shouldn't have devices able to interfere with more than one other.

The only thing I can think of that would explain it is a bad solder joint or via in the USB power supply that doesn't make good enough contact when cold to power more than one device but gets there after it has had time to warm up. You could get one of those $15 or so USB power meters, plug it between the USB port and your device and look at what happens to port voltage over time and when you plug a second device in to test this theory.

A bad PTC fuse could also do it but again, boards typically have one PTC or e-fuse per two ports at most, often one per port.
 

omgzombie

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That is some weird issue. On most platforms, USB host hubs only have two ports each, so you shouldn't have devices able to interfere with more than one other.

The only thing I can think of that would explain it is a bad solder joint or via in the USB power supply that doesn't make good enough contact when cold to power more than one device but gets there after it has had time to warm up. You could get one of those $15 or so USB power meters, plug it between the USB port and your device and look at what happens to port voltage over time and when you plug a second device in to test this theory.

A bad PTC fuse could also do it but again, boards typically have one PTC or e-fuse per two ports at most, often one per port.
Do you reckon changing the motherboard might fix the issue then? It's some kind of power issue but I'm not sure who's the culprit here. The SMPS or the motherboard.
 

InvalidError

Titan
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If the PSU was wonky to the point of causing simultaneous disconnection across all USB devices regardless of what they are plugged into, I think you'd have even greater issues than just USB.

Wouldn't hurt to know what the components actually are.
 

omgzombie

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I'm using a Gigabyte GA-78LMT motherboard and a 450w psu. I have a Amd phenom 2 processor which is running slightly overclocked and 8 gb 1666 ram and a Asus graphics card of 2 gb.
 

InvalidError

Titan
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If the PSU is as old as the rest of that system or a so-so/crap quality model, it would be worth replacing with something decent worth carrying over to a new build, especially if you are going to throw other new parts at it since a dying PSU could be the reason the original parts failed in the first place. If it happens to fix your USB problem and save your motherboard, great for you.

The other thing everything has in common is the chipset, though a chipset issue would also affect everything connected to it, not just USB. Maybe you aren't noticing other stuff also dropping out when it does?
 

omgzombie

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If the PSU is as old as the rest of that system or a so-so/crap quality model, it would be worth replacing with something decent worth carrying over to a new build, especially if you are going to throw other new parts at it since a dying PSU could be the reason the original parts failed in the first place. If it happens to fix your USB problem and save your motherboard, great for you.

The other thing everything has in common is the chipset, though a chipset issue would also affect everything connected to it, not just USB. Maybe you aren't noticing other stuff also dropping out when it does?
The PSU is actually old and a so-so model. Another thing i noticed is that in the 12v 8 pin socket I only have a 4pin connector plugged in. I know that's for CPU but I reckon that could be somewhat of an issue as well. I'm thinking about getting a new 500w psu which has a 4+4 connector instead of a single 4 pin connector for the 12v 8pin socket.
 

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