Mac Pro 3,1 Losing Power?

[bwillwall]

I've been struggling off and on with this Mac Pro for several days. It worked flawlessly until suddenly it started shutting off at random times. It had a dead PRAM battery, so then I replaced it and it worked perfectly for days, that is until I installed new RAM and a new GPU and the problem started again. It's like being messed with did something to it? Maybe unplugging the power supply caused it to lose some of its charge?

What happens is this, it works fine until suddenly theres a click sound and it immediately loses power. Again, it worked for days, and then other times it only worked for minutes or an hour or so.

 

[VAGDesign]

Backup your data and replace the hard drive you have your OS. It's not anything else, it's the drive that failing.

 

[netkas]

Had the same, turned out it's psu giving much less then 12V, ram is failing first then.

I took out my psu, disassembled it, cleaned it out of dust and it started to work fine again.

Carefully check all my posts in this thread - https://forums.macrumors.com/threads/your-mp-3-1-ram-temp.1895953/

 

[bwillwall]

Backup your data and replace the hard drive you have your OS. It's not anything else, it's the drive that failing.

And what makes you so sure of this?

 

[VAGDesign]

And what makes you so sure of this?

This:

...suddenly theres a click sound and it immediately loses power..."

 

[bwillwall]

This:

Ah ok. Thanks I will test it out!

 

[haralds]

This:

Amen...

 

[bwillwall]

This:

Amen...

Actually the click isn't coming from the HDD. I took it out and it makes that click sound when I shut it down manually still. It's either a normal sound coming from the PSU or motherboard or it has to do with something that's broken. Either way, it still fails when I boot from a USB drive without the hard drive installed.

 

[nigelbb]

I suspect that the click is coming from a dodgy power supply.

 

[1madman1]

The "click" is probably a relay. My 4,1 and 5,1 would shut off in a similar manner if I overloaded the PSU. If your system shuts off while doing something straining the new GPU you may need to find an alternate method to power it. Otherwise I suspect you may need a new power supply.

 

[VikNomad]

Can new video card be a culprit? If it has no power from extra connection and suddenly draws too much from PCIe lane?
Maybe 6 pin power cable is a problem. Just my $0.02

 

[netkas]

Just read my post, even your phrase " I installed new RAM " hints at it, the more ram you install, the more it sucks power off psu, and ram fails first if psu doesn't provide enough volts on its output.

 

[bwillwall]

Just read my post, even your phrase " I installed new RAM " hints at it, the more ram you install, the more it sucks power off psu, and ram fails first if psu doesn't provide enough volts on its output.

Okay but isn't it sort of dangerous to work inside a PSU? I don't really know what I'm doing with it. lol

 

[bwillwall]

Just read my post, even your phrase " I installed new RAM " hints at it, the more ram you install, the more it sucks power off psu, and ram fails first if psu doesn't provide enough volts on its output.

Okay but isn't it sort of dangerous to work inside a PSU? I don't really know what I'm doing with it. lol

 

[netkas]

Check voltage from power supply and on vram first with some monitoring utility

 

[bwillwall]

OK guys I tried testing the PSU, me and somebody else decided it must have something to do with the power supply. I broke down and bought a 3,1 PSU (which isn't very cheap) that I can return in the case it does not fix my problem. I will let you know what happens.

 

[bwillwall]

Not PSU, I'm returning it because there was no difference.

The resolution I found was actually resetting the PRAM. I had done this before, but somehow it had a problem again. There could be some sort of motherboard problem here but until this problem is reproducible I'm not spending any money on it as it's working great at the moment. If something changes I will post it.