Can someone please explain this red light?

[R_gui]

What does this light on the Mac Pro 2009 or 2010 mean? I have a Mac and after using too much power from using two gpus in the same slot by accident, and after turning it off, it won’t turn back on. Now, from time to time, maybe a few hours or a few days, it’ll turn of, but once it’s off, it’s off.

 

[MBAir2010]

The red light means you must stop your vehicle and wait for a green one.
I think that for headphones and sound.....if there is a toogle or switch, i think turm or reset that

 

[bsbeamer]

https://discussions.apple.com/thread/7660151

 

[crjackson2134]

from using two gpus in the same slot by accident

I’d like to see a pic of two GPUs jammed into the same slot. Did this involve using a hammer or was it a saw?

 

[Alex Sanders74]

Which LED is lit? There are a few....

If it's an OVERTEMP, which is red I can offer some advice.

Also, why aren't you using that GPU in Slot 1?