Mac Pro 3,1 USB issues

Intermittently, I have been having issues with the USB ports on my Early 2008 Mac Pro (3, 1). I start up the computer, and none of the USB ports work - a pop up windows says that it is searching for bluetooth keyboard/mouse because none are connected.

Sometimes, I can unplug and replug the USB keyboard a few times and it will somehow start working.

I've also noticed the issue with the USB ports on my Cinema display (at first I thought the ports on the display were not working, but I think it's that the computer's were not).

The only USB devices I have connected are:
- Cinema display
- iPhone charger
- Keyboard
- Mouse

I've noticed if I unplug the display, it seems to get better. But I can't imagine that those 4 USB devices were be too much power for a Mac Pro.

Is there anything else I can do to diagnose this or hopefully resolve it? I do not think it's an issue with the keyboard mouse because when the keyboard doesn't work, none of the USB devices work.

I am using OS Maverick.

cebseb said:

Have you cracked open your case lately? I have had odd things happen similar to what you're experiencing whenever my logic board was caked with dust.

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I did actually open my case just a few months ago to install some new RAM and I vacuumed the inside. This USB issue has occurred before and after the new RAM, so I do not believe that is the issue.

tigerintank said:

if you have access to another video card - try swapping it in.

I've seen issues where a faulty card was somehow pulling the psu down. causing issues with both external ports. issues went away with a new card.

if its possible to boot without a video card installed and remote in then guess that would work too.

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Unfortunately I do not have access to another video card. Is it possible to boot without one?

Is there any way to determine if it's somehow caused by the Cinema display? Is it possible that it's trying to use too much power and causing other ports to not function?

So... this problem has worsened and now my Mac Pro won't even boot - it is in a restart loop. I think it might have something to do with the video card, because during my last successful login, after logging in, the screen became pixelated and then the restarts began.

I'm wondering,

(1) How can I find out what video card(s) are compatible with the Early 2008 Mac Pro (3,1)?

(2) What is the least expensive card I could buy to just get the machine working? I only use it for email/internet at this point.

So, I ended up going to Best Buy and basically buying the cheapest thing I could find, in hopes it would work. I picked up a Geforce GT 610 2 GB. And... it booted up successfully (no boot screen of course).

Will this card be suitable? Like I said, I have pretty basic needs. But will I have any issues with the screen being laggy or choppy if the card isn't meant for Mac?