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Is it possible that bad RAM prevents Mac Pro 5.1 from powering up?

agazoo

agazoo

macrumors regular
Original poster
May 15, 2015
110
18
Hello,

Looking for an opinion,

My cMP 5.1, which I am using for gaming, has recently decided to quite on me midfight

It simply shutdown,
I wasn't able to turn it back on for a while. After plugging/unplugging power cables, it suddenly came back to life. Not for long. About 20 minutes later I died again. I then removed all add-ons (980 TI and Sonnet Card). No luck. Wouldn't turn on at all. I then removed all memory (aftermarket ECC from OWC 4gb sticks); Left only two, and some time later it came back to life

It is running now, but, I am not confident RAM it is.
I've seen RAM causing issues but never preventing system from powering UP. On the other hand, while trying different sticks I managed to power system once from about 10 secs, then shutdown.

Is it possible that SMC prevents system from starting after some critical equipment fault?

Thank you
 
Unlikely, it is pretty cold here :)
Dead sensor somewhere - quite possible - trying to diagnose
GPU is also running of the separate PSU ...

Going to run BF to see if it stable, so far with only two sticks of memory in, it appears to run ok
 
I would be very suspicious of any product from OWC. I have not had good luck with them, and would never order from them in the future. Here's just one thread from a member:

https://forums.macrumors.com/threads/owc-ssd-upgrade-2012-macbook-air-buyer-beware.1459847/

My supplier for RAM since 1986 has been:

http://www.datamemorysystems.com/ap...06ghz-md771ll/a-cto-mid-2012-memory-upgrades/

I have never received a bad stick of RAM from them in all those years.

But usually with bad RAM, the machine will power up fine, but just won't recognize the bad stick. Maybe there is something electrically wrong with the RAM????

Lou
 
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Perhaps you should start by putting your system back to standard spec (remove all adds to your system).

As for over heating, it certainly could be an issue if the CPU isn't directly cooled properly. You could run your MP in near freezing temperature but it would seize up if there was no direct cooling of the CPU.

1) remove added devices and check, if it runs properly you have to investigate which item added is at fault and possibly associated software. (This includes RAM, drive sleds etc.)
2) check traditional methods of CPU and GPU cooling (the internal fans are working properly and there is no blocking of air flow in/out).
3) power supply - check the power supply itself and all connectors and what they are connecting to (as in looking for potential partial shorts.

This is where I would start. Then again it could be something far simpler and over looked.
 
How is external GPU PSU triggered?

Sounds like power draw too high then tripping main PSU protection.

Next time it quits, unplug power and then hold power button down for 5-10 seconds

Replug power and try power button

If that works, you are drawing too much current or main PSU dying
 
GPU PSU I just turn on manually before I power up the system; I do have occasional glitches like screen going off, but this is probably related to my KVM which is having trouble with 4k at 60z.

System appears to be running fine at the moment with original RAM that came with my nMP, i had laying around, had no idea it was compatible.

Will see what happens next ...

I would be really surprised to see PSU go bad (not that it doesn't happen), but I know so many G5s still running fine including my own (24/7 since 2005).

TBH I had issues with OWC memory before (in G5); And I had issues with their SSD for nMP (replaced under warranty, but still ... )
 
Last edited:
Not Memory, Still Dies ...
Not turning on ... holding power button not helping ...
Will try again tomorrow, could be a temperature ... may be I messed up thermal compound during CPU upgrade
 
To be 100% clear on GPU PSU, most of these need to be more then "turned-on"

The PC Power Supplies requires 2 pins to be shorted. Requires switch son and then the shorted pins. (typically referred to as the "paperclip trick" as that os easiest way)

The ones that go in a OCD also require a trigger, typically a 12V feed to a Molex connector.

My apologies if you already know this and have been using one of these methods.

I get at least 1 email a week from someone furious that their new GPU won't work and frequently it is a result of not triggering the PSU.
 
how long ago did you upgrade the CPU? have you been monitoring the temps?

might be worth pulling the GPU and punting in the old one (if you have it).
 
I've had laptops with bad ram, they don't like booting up at all. or make beep noises!!!!

if you have replacement ram that you just bought and it won't boot with them installed. tell them you want your money back

if your computer boots, run apple hardware test in extended mode.
if apple hardware test passes, then the genius tests will probably pass too.

apple hardware test will tell you if you have any problems with the temperature sensors. this isn't a guess. it clearly will give you an error code if there is anything wrong with your temperature sensors.



if you have problems turning on the computer, you should clear the smc first.

unplug everything and wait 45 seconds ( the so called apple way ) or unplug everything and hold down the power button for 5 seconds to drain the capacitors


I've had intel processors with heating issues. you really have to mess up your thermal compound or the fan has to die to get them to actually burn up. an intel cpu will easily hit 180 until it shuts down
this saves the processor from blowing up.

i had a problem with a water cooling system. the deal with water cooling is if the fan breaks and the water does not have a chance to chill, the cpu will just boil that water like a coffee pot and the water gets hotter and hotter, and then finally shutdown hard. , and even with that, my intel cpu did not blow up

if your cpu blew up you should see some obvious signs when you remove the fan

intel stands behind their warranty. if you bought the cpu in a box, then call intel and I'm sure they will replace it free of charge, they let me replace a pentium years ago, i don't think anything has changed. if you bought the cpu as a component, then you have to return it to the store.

always buy cpus and hard disks in retail boxes.
 
Last edited:
MacVidCards said:
To be 100% clear on GPU PSU, most of these need to be more then "turned-on"

The PC Power Supplies requires 2 pins to be shorted. Requires switch son and then the shorted pins. (typically referred to as the "paperclip trick" as that os easiest way)

The ones that go in a OCD also require a trigger, typically a 12V feed to a Molex connector.

My apologies if you already know this and have been using one of these methods.

I get at least 1 email a week from someone furious that their new GPU won't work and frequently it is a result of not triggering the PSU.
Click to expand...

I have paper clipped pins on the main connector (one which normally goes to MoBo) and connected 8 pin PCIe connectors to the card. Nothing else; When I turn on my Mac, I also flip a switch on PSU. Card is Gigabyte 980 TI, non flashed; I am on contract in Europe, shipping here from US will trigger 21% VAT + other customs charges. Maybe I'll get it flashed next time i go to US.

What exactly is OCD, trigger? Google says OCD is "Obsessive-compulsive disorder" I doubt this is the condition my Mac is having :)

In any event, I was unable to get it running yesterday (SMC didn't help);

This morning, after another round of SMC reset, it started just fine.

I am investigating three issues (1) CPU/GPU temps, quite possible (2) Bad or Incomplete Secondary PSU setup ( still, there is no connection to Mac PSU from GPU, is it possible it is drawing too much over PCIe? )
and finally (3) Main PSU or MOBO is going out; I had 980 in it for awhile powered by internal PSU only; Possibly it caused lazy damage of some sort ...

Thanks for assistance, everyone :)
 
agazoo said:

I have paper clipped pins on the main connector (one which normally goes to MoBo) and connected 8 pin PCIe connectors to the card. Nothing else; When I turn on my Mac, I also flip a switch on PSU. Card is Gigabyte 980 TI, non flashed; I am on contract in Europe, shipping here from US will trigger 21% VAT + other customs charges. Maybe I'll get it flashed next time i go to US.

What exactly is OCD, trigger? Google says OCD is "Obsessive-compulsive disorder" I doubt this is the condition my Mac is having :)

In any event, I was unable to get it running yesterday (SMC didn't help);

This morning, after another round of SMC reset, it started just fine.

I am investigating three issues (1) CPU/GPU temps, quite possible (2) Bad or Incomplete Secondary PSU setup ( still, there is no connection to Mac PSU from GPU, is it possible it is drawing too much over PCIe? )
and finally (3) Main PSU or MOBO is going out; I had 980 in it for awhile powered by internal PSU only; Possibly it caused lazy damage of some sort ...

Thanks for assistance, everyone :)
Click to expand...




if it boots run apple hardware test in extended mode.

https://support.apple.com/en-us/HT201257

if it dies or crashes or gives an error, well , there you go. you will have valuable information
I've seen old g4s fail apple hardware test just because the cpu was clocked faster then what the computer was shipped with




if you misplaced your apple hardware test cd, you can download images from
https://github.com/upekkha/AppleHardwareTest
 
I don't think Hardware Test would work with non-flashed video card :-(

I did CPU stress test, and while it gets hot (91C), there was no fault;

Time to try BF4 with temp monitor on
 
agazoo said:
I don't think Hardware Test would work with non-flashed video card :-(

I did CPU stress test, and while it gets hot (91C), there was no fault;

Time to try BF4 with temp monitor on
Click to expand...

well, then your going to to have to remove that video card and do the test.
 
Problem is it fails without any load. It just died on me again temps were 39C;
Seems like I will have to get Mac card and run hardware tests ... something isn't right with the hardware
 
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** I noticed that one CPU is getting considerably hotter then the other (if you touch); Then I noticed that if you pull processor board out and plug it back in, system starts (for some time); I tried Intel Extreme Overclocking tool and it only shows presence of only one CPU (while other tools were showing two; CPUs are X5690;

I removed on CPU (from socket right under PSU), system didn't start; I reinstalled it back and removed another one. System has stated and runs ok atm with just one CPU (1/2 or RAM of course);

One interesting observation is that thermal compound on both CPU was kind of liquid;

Will see what happens next
 
blacka4 said:
i would get some new thermal compound and replace it on both CPU's it being liquid doesn't sound right. i
Click to expand...

I used Artic Silver 5, had some good reviews at a time I did upgrade(1.5-1 years ago)
 
agazoo said:
** I noticed that one CPU is getting considerably hotter then the other (if you touch);
Click to expand...

You use Hardware Monitor? You should also check the temperature of your Northbridge!
There are quite a few number of users who found their Northbridge running very hot, could be it affects the CPU that is running hot too, as Northbridge seats half under the cpu!

Something totally different, I had a 5.1 quitting on me too a while ago, no real reason for it... I found a lot of dust in the PSU, after emptying a can of air I didn't have the problem anymore.
 
Still Fails,

Redid thermal compound on CPUs and Northbirdge (temps are 35-40 for CPU and 62 for North Bridge on Idle); Tried various single CPU configurations; Been working for a while, and then failed overnight;

Considering that with only one CPU system works much longer, it could very well be a PSU problem,

I also noticed "oily" spots of melted resin of some sorts right underneath CPU sockets . Never seen anything like that, still Investigating ....
 
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