USB Devices Power Draw Calculation

Gergelyc · November 18, 2020

Hi Guys!

Sorry if this topic has been coeved, I did a quick search but I did not find any topic matching my question.

I have a KVM switch to switch between my work and personal computer in this HO world. (I am from Germany)
https://www.amazon.de/-/en/UGREEN-Printers-Scanners-Keyboards-Headset/dp/B01N6GD9JO/ref=sr_1_3?dchild=1&keywords=kvm+3.0&qid=1605685060&sr=8-3

I have a Logitech Pro (wired) X Keyboard
Razer V2 Bazilisk
Blue Yeti (Original)
and a Lenovo 500 full HD (https://www.amazon.de/-/en/gp/product/B0821RB61V/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1) connected to the KVM.

I got the Lenovo yesterday and I was playing around with the Nvidia broadcast and I noticed at 1920x1080p 30fps the picture had very common artifacts. I thought Nvidia broadcast is in its infancy, doing some missteps. I noticed while talking to my friend while using the webcam, the audio would drop out. Further investigation revelaed the drops are more frequent with more moevement on my end.

I downloaded https://superuser.com/questions/549761/how-to-test-power-capabilities-on-usb-3-0-hub (USBDeview) and I confirmed a suspicion of mine. The Keyboard + Webcam together has 1000ma power draw, not counting the bazilsik + 100mA and the yeti +100mA. The wireless and Mystic Light devices are connected to the computer directly.

From the wiki page of USB I got this part:

Power and charging

As with earlier versions of USB, USB 3.0 provides power at 5 volts nominal. The available current for low-power (one unit load) SuperSpeed devices is 150 mA, an increase from the 100 mA defined in USB 2.0. For high-power SuperSpeed devices, the limit is six unit loads or 900 mA (4.5 W)—almost twice USB 2.0's 500 mA

Do I understasnd correctly that USB 3.0 (Passive) can only carry 900mA of power (or in that ballpark?) As such the artifacts, drop outs are happening because the KVM switch is underpowered? If so buying a POWERED 3.0 usb hub, connecting all devices into it and then into the KVM will that solve my problem?
If not what would be your other recommendations?

Regards,
Greg

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