[Solved] gpu red light motherboard and failing to post most of the time

[abaabaabaaba4]

I have had this system since 2011 and had no problems until recently, a majority of the time when I turn the computer on the red light next to the gpu on the motherboard comes up and theres just a black screen and it doesn't go any further then that. Occasionally it is a cyan or a pink screen. I will switch it off at the back and unplug the power give it a few minutes and try again and sometimes it works but it mostly doesn't. Using a compressed air can I have got rid off dust inside including in the pcie slots and the gpu heat sink and sometimes the computer boots after that but other times it doesn't. It has been becoming more and more frequent recently and I have considered just buying another gpu but am unsure if the issue would be fixed, I was able to test using a friends gtx 650 and while the apple logo came on nothing more happened so I am concerned that if I just buy another card it might not work.

Also to note a few months ago I changed the system definition from mac pro 3,1 to iMac 14,2 I think and removed the null cpu power management kext to allow the cpu to speed step and turbo as I realized for many years it had been running at 3.4ghz constantly. The red light issue has started happening a few months after that and as I said has increased in frequency so I am assuming that the two are unrelated and its just a coincidence but Im not sure.

Any help would be much appreciated

 

[P1LGRIM]

Any help would be much appreciated

On a six year old machine the CMOS battery probably is due for replacement.

 

[abaabaabaaba4]

Oh right thanks I didn't think of that, so could that be causing these issues then?

 

[P1LGRIM]

Oh right thanks I didn't think of that, so could that be causing these issues then?

It could and it's the cheapest/easiest place to start your diagnostic process.

 

[abaabaabaaba4]

Ok, I just happen to have lots of those cr 2032 batteries so I'll try it, I just want to get into the bios and take pictures of it so I don't lose the settings but Ill let you know if it works when I try it.

 

[abaabaabaaba4]

Right I've changed the battery and theres no change it still isn't coming on, I cant even get into the bios with the 460 in I have to use the 650 which makes me think this is just a case of the graphics card being dead/dying. I don't mind buying another gpu just to get things working but my only concern is compatibility, that 650 works fine in another computer with the exact same build of mavericks and I worry if I buy something it wont work.

 

[flilot]

The newer nVidia cards require use of the nVidia Mac web driver, there's a list here.

If you do buy a new card, be sure to try and stick to the supported cards list available on this very site here.

 

[abaabaabaaba4]

Ah right ok thanks, see the mavericks build I've got is 10.9 (13A603) and I notice on that list that its missing, also Im not sure but reading that stuff Im getting the feeling that 650's should be supported natively and I don't think any drivers were installed on the system that the 650 works fine in Im just worried cause it doesn't get past the apple logo when I use it in my machine so

 

[abaabaabaaba4]

update: I changed the psu cables and now the computer is booting up fine every single time so it was a power supply issue, thanks to everyone for your help!