I built a PC at the end of last year and ever since I've been unable to use my second GPU without disabling USB connections

Posted by castleyankee@reddit | buildapc | View on Reddit | 7 comments

Troubleshooting Help:

What is your parts list?

Describe your problem. List any error messages and symptoms. Be descriptive.

Whenever I enable a second monitor through my second GPU, my wired keyboard immediately stops communicating with the PC. It doesn't power down, and if any keystroke is engaged at the time it cuts out it acts as if I'm holding that key down. This problem extends to xbox wireless receivers, wired connections to an xbox controller, webcam, and any other USB connection except for my mouse, an external USB hard drive, and a backup wireless keyboard.

If I unplug/replug the wired keyboard it repeats the freeze communications thing described above immediately. The other USB connections don't register at all or even power on until I disable the second monitor and unplug/replug them. Then they work just fine.

I do not receive any error messages. The only notification received is the USB connected/disconnected tone when I unplug and replug my keyboard.

List anything you've done in attempt to diagnose or fix the problem.

I was having issues with my keyboard early on. I'd receive the USB disconnect tone followed shortly be the connect tone, the keyboard backlight would flash, and then the keyboard would not send any input until unplugged/replugged. It happened seemingly randomly, always with only a single monitor on at that point, and only affected the SteelSeries wired keyboard. The mouse and Red Dragon wireless keyboard did not have this issue. Disabling a setting "USB Selective Suspend" entirely fixed this issue so far permanently.

I've purchased a watt meter to see if I'm using way more power than I should be, and I'm really not sure that I'm reading it right. With both GPUs handling a single display each it reads ~150W. With only the main GPU handling only the main display it reads ~400W There's also a "watt overload" screen that displays 3680W, and I have no clue what that is or means.

Parts List

My big concern is that my MoBo isn't routing sufficient power to handle the GPUs and USB peripheries. If the wattage estimator on PCPartPicker and/or the watt meter readings are reliable, then the PSU should be plentifully overpowered. If that is the issue, then I'd like help identifying whatever spec on this MoBo is behind that. If that is not the issue, then the problem lies somewhere outside my PC literacy/stomping grounds.

I'm headed out to do some maintenance work on the beater truck to let this post gather some replies from more knowledgeable people than I. If you need more information just lmk what I need to describe, I should be able to get back to you fairly quickly.

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keegorg@reddit

What do you mean by 2nd GPU? GPU usually refers to the video card itself.

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castleyankee@reddit (OP)

I mean the 3060. My main gpu is the 4070 Ti S

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keegorg@reddit

My best guess is your power supply can't power both. Video cards use a lot of power. I'd bet you'd need like 1200 watts (total guess) to run 2 cards. Search youtube for videos on how to run multiple cards.

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castleyankee@reddit (OP)

I ran both of these cards in my previous build on a 750w PSU. Is it possible that this 1000w PSU simply doesn't divide and deliver power as well despite having an overall higher throughput cap? I could see that being a thing but lack the expertise to know if it is.

I'd wanted to go 1200w or higher when I originally built this but nothing good was in stock, prices were going up and 1000w was allegedly good enough. So in the end I wouldn't label having to upgrade a catastrophe, I'm just a bit surprised at how far off the wattage estimator was in that case. Over 200w

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keegorg@reddit

if you used a wattage estimator, its gonna have better data than I do. I would also trust that. I guess I missed that in your original post.

Its pretty rare to run 2 gpus... I'm assuming you have a specific need for both. I believe either one of those cards would handle 2 (or more) monitors without the need for a 2nd video card.

Running 2 video cards is fairly rare, it might be something like your mobo doesn't even support 2 cards.

Digging into the parts list, Everything looks solid. Your HD situation is kinda cancer, but it shouldn't affect video performance in any way.

IDK man.. I'm not seeing anything obvious. Might need to test any non-working parts in a different PC.

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castleyankee@reddit (OP)

At one point semi-recently I was connected to 7 different monitors for work. Not that they were all in use all the time but they each had a function.

That's no longer the case but I still have the 2 GPUs so I figured why not let one burn VRAM at max settings and let the other one render the side monitors. So it's not a big urgent need or anything. Just wanted to use the thing I had to buy