I recently bought a KVM switch to switch between a single-monitor tower setup and a laptop + extra monitor setup (meaning the laptop and tower share one monitor.) I've started experiencing BSOD's on both machines that I'm PRETTY sure are a result of using the switch. To be honest, with the infrequency of the BSOD's and the functionality and convenience of the set-up, I really don't feel like giving it up. On the tower, (which has generally decent hardware but nothing mind-boggling,) I'm running some mild excel data crunching for an extended period of time. My question is, assuming the switch looks the same to the computer as plugging and un-unplugging my mouse and keyboard every few minutes (when I make the switch,) is that using up a large amount of memory and, combined with the running excel macro, causing the crashes? Or does hot-swap hardware not use that much memory?

WAY too long; didn't read:

  • Use a KVM switch
  • Experiencing BSOD's on both machines that I'm switching between
  • Running data crunching excel macro on one machine

  • Question: Is the macro + hot-swapping causing the BSOD's?

  • Your assumption that using the KVM switch is like "plugging & unplugging" is incorrect. PS2 ports, for starters, are not hot-pluggable. The KVM switch will always electrically load the PCs' ports so that the PCs cannot detect when the KVM has selected that PC or when that PC has been deselected. A properly operating KVM switch should be undetectable by the PCs. There are no "hot-swap events"; hence your memory question is irrelevant. You need to read the messages in the BSODs instead of guessing at a cause. – sawdust Jan 26 '12 at 20:20
  • The KVM switch is entirely USB. I assumed that the computer recognized it as an "unplug" because when I would switch from one to the other, the "disconnecting" computer would give the "hardware-unplugged" little audio notice. The message of the latest BSOD said something about "memory ______," (I don't remember what, specifically,) so, again, I made the assumption that there was some sort of memory overload. I don't know a lot about BSOD and their causes to begin with, so I'm a little behind. – Quintis555 Jan 26 '12 at 20:45
  • You should disable automatic restarting after a BSOD. In Win7 go to Control Panel / System / Advanced System Settings / Advanced / Startup and Recovery. BTW my KVM switch, which has USB connections, does not generate any USB events. – sawdust Jan 26 '12 at 21:17
  • @Quintis555: Obviously it is going to say something about memory. Whatever created the fault resides in memory, be it a file system driver, USB driver, web browser, etc etc etc. – surfasb Jan 26 '12 at 23:52

Plugging and unplugging a keyboard, mouse, and monitor shouldn't cause any significant memory usage.

If you're using PS/2 connections for the keyboard and mouse, the OS probably doesn't even notice. If they're USB, the OS will notice and run a bit of code to handle the event, which might use a little memory for a short time, but it shouldn't cause any memory to remain in use long-term. Repeated switches shouldn't cause any build-up.

Anyway, memory usage shouldn't cause a BSOD like that. If there's not enough RAM, Windows should page out parts of Excel's memory to the paging file. You'd hear disk thrashing and your system would perform more slowly, but it should still remain stable.

Your BSOD problem is probably caused by something else.


It should use no memory. When you say you are un-plugging the mouse and keyboard, are you just switching input/output from desktop PC to laptop of vice versa?

The KVM should allow easy swictchin of one keyboard, mouse and monitor between two( or more) computers without issue.

Make and model of KVM might help.

  • Yeah, what I meant was that I'm switching between the two displays, but what I'm assuming is that when I switch away, that looks the same to the computers' OS as unplugging the mouse, keyboard and display. It's a Rosewill RKV-2UC; I'm really happy with it, and even more so if it's not even the cause of the problems. But if, like you say, switching doesn't take much memory, then that at least answers my question, even if it doesn't' solve my problem :) – Quintis555 Jan 26 '12 at 16:04

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