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Discussion Starter · #1 ·
Hi folks,

I'm running a Mac Pro circa 2009. Great machine, no complaints.
running El Capitan

Dual monitor set up, DELL and HP monitors (probably same vintage 2009)
Graphics Card - ATI Radeon HD 5870 1024 MB

Once in a while, as I'm sitting on my desk, sometimes, I knock the desk,
or my knee taps the the underside of the desk. or if I drop something on top of my desk
(its a L shaped desk) my monitors go blank. They still have power but they are in
sleep mode, nothing being displayed (as if there was no signal) The mac is still on and the
only way to regain control of my pc is to hold power and re-start and voila everything works again
until the next vibration.

Could this be a lose connection somewhere? I figure since both monitors are affected
perhaps its the graphics card?

anyone ever had a situation like this before?


17,352 Posts
sounds like graphics card to me. First thing Id try is pulling it and reseating it. Next is an alternative card I guess. Something is getting knocked in the Mac Pro. I recall the daughter cards being a little fragile and dicey as well, though Im not sure if that would affect the graphic but who knows?

Premium Member
42,901 Posts
As groovetube suggests, I found the way these big, heavy graphics cards were seated to be a little unstable in the MacPro. That unit has four slots for a graphics card, so seat it in a different slot when you reseat. If you use the bottom slot, you can shim up and stabilize the card a little using some non-conductive material like an eraser. That's worked for me.
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