I haven't seen this before, but to be sure I tried this on a few of our Dell 960's and 990's. Neither had the issue of screen flickering on the vPro client. I would suggest updating to the newest BIOS and drivers, and try again.
Thanks Adam. I'm definitely on the latest BIOS and drivers as far as what's available on Dell or Intel's site (graphics, nic, SOL, IME; etc). I almost wonder if there's some weird L2/L3 issue like excessive packet fragmentation or TCP windowing errors or something.
This is actually an expected behavior for Intel’s KVM when display is working in VGA mode (some BIOSes and DOS) . It is caused by integrated Gfx HW limitation of Intel's KVM for showing Sprite while the display is in VGA mode – in this mode it can’t show the display image itself and the Sprite at the same time so when it shows the Sprite User Periodic Notification it can’t show the screen itself.
For this reason the Sprite User Periodic Notification is done once in about 10 sec (instead of 3 sec for non-VGA mode).