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- Sep 22, 2011
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I resolved an annoying "character skipping" behavior of my USB keyboard by separating my CPU power (8-pin) and PCI-e power (8-pin) onto separate PSU "rails." Details are below. I'm sharing to help others who might observe this and to ask if anyone else has observed this.
After I installed a Sapphire Pulse RX580 in my old Socket 1156 system described here, my USB keyboard would occasionally "skip" characters. The skipping came at what appeared to be random times. By "skip," I mean that some of my typed characters were not actually typed. This problem did not happen when I had an NVidia 9800GT graphics card installed.
Since this seemed to be clearly a power problem (problem only started after upgrading to the more power-hungry RX580), I examined my PSU (a SeaSonic Focus 750W Gold) and found that I had both the CPU (8-pin power cable) and RX580 (8-pin power cable) connected to the same "rail." My PSU is semi-modular with permanent CPU and PCI-e power cables on one rail and modular peripherals/PCI-e sockets on a separate rail. I disconnected the permanent 8-pin PCI-e power cable from my RX580 (leaving it disconnected) and replaced the RX580 power with a modular PCI-e power cable connected to the second rail of the PSU.
I am no longer experiencing the skipped characters after making this power cabling change.
Apparently, having the CPU and RX580 powered from the same PSU rail created enough system noise to affect USB performance.
After I installed a Sapphire Pulse RX580 in my old Socket 1156 system described here, my USB keyboard would occasionally "skip" characters. The skipping came at what appeared to be random times. By "skip," I mean that some of my typed characters were not actually typed. This problem did not happen when I had an NVidia 9800GT graphics card installed.
Since this seemed to be clearly a power problem (problem only started after upgrading to the more power-hungry RX580), I examined my PSU (a SeaSonic Focus 750W Gold) and found that I had both the CPU (8-pin power cable) and RX580 (8-pin power cable) connected to the same "rail." My PSU is semi-modular with permanent CPU and PCI-e power cables on one rail and modular peripherals/PCI-e sockets on a separate rail. I disconnected the permanent 8-pin PCI-e power cable from my RX580 (leaving it disconnected) and replaced the RX580 power with a modular PCI-e power cable connected to the second rail of the PSU.
I am no longer experiencing the skipped characters after making this power cabling change.
Apparently, having the CPU and RX580 powered from the same PSU rail created enough system noise to affect USB performance.