Flashing Power Light - Mac Pro not booting

[h4lp m3]

Just to let everbody know:
I ended up selling it as I didn't want to spend to much money on it to MAYBE work.

I just had the same blinking light problem with a mac pro 3,1. It was the video card .

 

[martyr]

Just wanted to add on here that I'm having the *exact* same issue. I have a 4,1 Mac Pro that has been flashed to 5,1 and upgraded to 2 x 6-core CPUs.

I, too, followed the step-by-step guide in the 2009 Technician PDF where you remove everything but the power supply and step-by-step add piece by piece. Everything goes fine with various diagnostic lights until I connect the processor and ram with the processor tray.

Once I do that, it turns on and the power light just flashes white continually. No powering off or anything. No memory diagnostic lights or CPU diagnostic lights. Everything looks fine except for the blinking power light, no chime / speaker feedback and no video. Fans spin up just fine.

I have 8 different 16GB sticks of RAM and I've tried all by themselves in Slot 1 of Processor A (with only Processor A installed), as well as in Slot 2, 3 and 4.

I have swapped the CPUs and that didn't help anything.

I'm out of ideas at this point. Open to others.

I have literally just purchased another Mac Pro 4,1 on Kijiji and will be picking it up tonight. Will try and swap the trays, etc. to see if I can get it working and narrow down the root cause. Any ideas from you smart lot, would be appreciated.

My goal here is to fix this Mac Pro to gift it to my neighbour friend for Christmas.

Cheers!

Josh


Btw, current state of things attached.

 

[tsialex]

Just wanted to add on here that I'm having the *exact* same issue. I have a 4,1 Mac Pro that has been flashed to 5,1 and upgraded to 2 x 6-core CPUs.

I, too, followed the step-by-step guide in the 2009 Technician PDF where you remove everything but the power supply and step-by-step add piece by piece. Everything goes fine with various diagnostic lights until I connect the processor and ram with the processor tray.

Once I do that, it turns on and the power light just flashes white continually. No powering off or anything. No memory diagnostic lights or CPU diagnostic lights. Everything looks fine except for the blinking power light, no chime / speaker feedback and no video. Fans spin up just fine.

I have 8 different 16GB sticks of RAM and I've tried all by themselves in Slot 1 of Processor A (with only Processor A installed), as well as in Slot 2, 3 and 4.

I have swapped the CPUs and that didn't help anything.

I'm out of ideas at this point. Open to others.

I have literally just purchased another Mac Pro 4,1 on Kijiji and will be picking it up tonight. Will try and swap the trays, etc. to see if I can get it working and narrow down the root cause. Any ideas from you smart lot, would be appreciated.

My goal here is to fix this Mac Pro to gift it to my neighbour friend for Christmas.

Cheers!

Josh


Btw, current state of things attached.

EFI_DONE is off when you press the DIAG button? If is not lit, you have a brick/dead backplane.

 

[yakult121]

Hopping on this thread as I have the same problem for a Mac Pro 2010.

OVTMP CPUx lights up briefly when connected to power. 5V STBY comes on when DIAG button was pressed. Nothing happened.

Left the Mac Pro alone for nearly 4 days. I’ve just plugged the machine into power. Still the same. Next, removed all RAM chips, and plugged back into power.

Wow, The machine powered up! White power button blinked couple times then it powered down.

Next I tried putting back the RAM chips. Nothing happening.

Polyfuses causing the troublesome non boot?

 

[yakult121]

I've replaced the Logic Board and now it boots. Paid a pretty penny for the replacement Logic Board...

 

[jscipione]

Tried, didn't work.

What I also did by now, was replacing the battery on the motherboard.
What kinda confuses me though is that the one that was in there was a CR2025 and it seems that there actually should be a CR2032 inside.

Could this maybe cause it?
Which battery do you guys have in your 4,1's?

The correct part to use is BR2032 which is the high temperature range tolerance version of CR2032. However CR2032 are cheaper and more available and generally work fine just might not last as long. CR2025 seems like it is essentially the same as a CR2032 just a bit thicker slightly supporting higher wattage output and it should also work fine.

All that said, the battery is probably not the main issue here.

 

[supaklaw1]

Had this happen last week, and it was one RAM chip. Using Mac Fans Control I see my DIMM risers had been running excessively hot despite everything else being decently cool w fan system.