MP 1,1-5,1 Mac Pro 5.1 (flashed 4.1) Shutdowns by GPU

[Romitomi]

Hello everybody
I'm using two macpros 4.1 upgraded to 5.1 with two xeon x5670 cpu's. both are equipped with a flashed gtx 680 2GB. With both of them, i have some issues with sudden shutdowns while higher gpu loads (multiple Instances of CAD software open). since i brought one device to a mac specialist, who run a deep level diagnostic and he told me that the issue is caused by a faulty graphic card i bought another used gtx680, but the shutdowns persist. So I think it's highly unlikely that all 3 graphic cards are faulty, and also highly unlikely that the psu's are not working properly in both mac's. I suspect, that in cases of high gpuload the graphiccards pull to much power for a little instance so the power supply breaks down and causes a restart, but i have no idea if its true or how to solve it.

Anybody any Idea?
thanks a lot.

 

[KeesMacPro]

There are different versions of the GTX680 with different power draw.
What PCIe connectors are on the card and how are they powered at the moment?

 

[anarchi]

I don't know whether it needs to be done or not, but the so-called "Pixlas mod" is supposed to solve the GPU-draws-too-much-power problem. It looks daunting, but is relatively easy to do. You can find information and "how tos" in lots of places. Here (https://thehouseofmoth.com/mac-pro-pixlas-mod/) for example.

 

[Romitomi]

There are different versions of the GTX680 with different power draw.
What PCIe connectors are on the card and how are they powered at the moment?

one card has a 1x8pin/1x6pin connection, the other two have 2x6pin as in the picture

 

[KeesMacPro]

I don't know whether it needs to be done or not, but the so-called "Pixlas mod" is supposed to solve the GPU-draws-too-much-power problem. It looks daunting, but is relatively easy to do. You can find information and "how tos" in lots of places. Here (https://thehouseofmoth.com/mac-pro-pixlas-mod/) for example.

I agree that the PIXLAS is a very good idea in general, but for almost all GTX680 is not necessary(GTX680 classified maybe).

one card has a 1x8pin/1x6pin connection, the other two have 2x6pin as in the picture

I see 2 mini 6-pin >6pin cables: should work fine ...

 

[Romitomi]

I don't know whether it needs to be done or not, but the so-called "Pixlas mod" is supposed to solve the GPU-draws-too-much-power problem. It looks daunting, but is relatively easy to do. You can find information and "how tos" in lots of places. Here (https://thehouseofmoth.com/mac-pro-pixlas-mod/) for example.

thanks for that input, so it seems really to be an issue as i suspected...

 

[KeesMacPro]

thanks for that input, so it seems really to be an issue as i suspected...

IMO Pixlas is one of the best mods for the MP 4,1/5,1 .
The idea is that the GPU draws its power directly from the PSU , and not through the mainboard.

Nonetheless, I've never read/heard of a GTX680 that triggers shut down due to power draw.
The GTX680 power consumption is moderate and the MP can handle it without problems.
The 4,1/5,1 PSU is rated for 980 W.

So i suspect the issue is related to something else e.g. CPU, CPU tray or NorthBridge.

Could you post a screenshot of the Temps (e.g. MacsFanControl/ iStats) at idle and one under load?

 

[Romitomi]

IMO Pixlas is one of the best mods for the MP 4,1/5,1 .
The idea is that the GPU draws its power directly from the PSU , and not through the mainboard.

Nonetheless, I've never read/heard of a GTX680 that triggers shut down due to power draw.
The GTX680 power consumption is moderate and the MP can handle it without problems.
The 4,1/5,1 PSU is rated for 980 W.

So i suspect the issue is related to something else e.g. CPU, CPU tray or NorthBridge.

Could you post a screenshot of the Temps (e.g. MacsFanControl/ iStats) at idle and one under load?

This is idle


and this is few seconds before a shutdown

 

[mikas]

I don't think you can stress GPU that much with ArchiCAD (what's your AC version in use?). GTX 680 should be powerfull enough for ArchiCAD. I can barely get a Vega 56 top 20-25% while rotating a complex 3D model continuously. See pic. GPU history spikes.

Might be some other apps eating your resources . Maybe try checking the shutdown cause with terminal:

log show --predicate 'eventMessage contains "Previous shutdown cause"' --last 24h

Shutdown codes Mac

You might want to try shutting down without Chrome, Spotify and all the extra stuff. If it helps, and shutdowns disapperar, you know how to proceed. Start adding those other softwares one at a time, and testing every added configuration.

Then again, it might be power supply. It's old allready, and maybe you don't it's usage history and so on.

And of course it might be GTX680 as you suspected. It's odd though that you have it in 2 machines equally.
But I guess your software is the same selection with both Macs, that's why I'd suspect software first.

edit. as a sidenote, your CPU B delta (heatsink versus diode difference) grows significantly compared to idle, with just a little bit of load. Temps are low, but delta is bigger than I think it should be at that temperature. At least comparing to mine and your own CPU A delta.

 

[Romitomi]

I don't think you can stress GPU that much with ArchiCAD (what's your AC version in use?). GTX 680 should be powerfull enough for ArchiCAD. I can barely get a Vega 56 top 20-25% while rotating a complex 3D model continuously. See pic. GPU history spikes.
View attachment 1758581
Might be some other apps eating your resources . Maybe try checking the shutdown cause with terminal:

log show --predicate 'eventMessage contains "Previous shutdown cause"' --last 24h

Shutdown codes Mac

You might want to try shutting down without Chrome, Spotify and all the extra stuff. If it helps, and shutdowns disapperar, you know how to proceed. Start adding those other softwares one at a time, and testing every added configuration.

Then again, it might be power supply. It's old allready, and maybe you don't it's usage history and so on.

And of course it might be GTX680 as you suspected. It's odd though that you have it in 2 machines equally.
But I guess your software is the same selection with both Macs, that's why I'd suspect software first.

edit. as a sidenote, your CPU B delta (heatsink versus diode difference) grows significantly compared to idle, with just a little bit of load. Temps are low, but delta is bigger than I think it should be at that temperature. At least comparing to mine and your own CPU A delta.

Thanks for your comprehensive answer.
As you suspect, i also thought i may be the power supply. but the mac specialist didn't confirm that and sees the graphic card as the main suspect, so i directed my problem solving efforts in this direction. As you say, it's old hardware and you never know what is its history. It applies to the computers itself and also to the graphic cards. thats why i bought a new (used ;-)) one. But now i think I would be damn unlucky if i got 3 bad graphic cards.
So there may be just a little capacitor in the psu which is working fine in normal cases and has just a little glitch for a moment during higher loads, what causes the shutdowns. I'm not a specialist, but that's how i imagine it to work. But one the other side: both machines with the exactly same problem? both PSU aged the same way? feels somehow even improbable.
So you might be right: it could be the software. But shouldn't be the basic functionality protected by the os? Can software cause such kind of problems? BTW: AC Version: 23

 

[TzunamiOSX]

one card has a 1x8pin/1x6pin connection, the other two have 2x6pin as in the picture

Did you get the shutdown on the 1x8pin/1x6pin card? If yes, the current can distributed there in proportion of around 66% to 33%. So you can get a emergency shutdown really fast. On a 2x6pin the proportion is 50/50.

 

[Macschrauber]

I dislike the temperatures at idle a lot.

was that really idle? Measure it again after the machine was off a few hours. the Cpu sensors should have a delta of 2-3 Celsius when the machine is sitting there doing almost nothing. Like 32, 34, 36 Celsius for the 3 readings.

 

[tsialex]

Did you checked your Mac Pros PSU manufacturer?

ACBel made PSUs are known to have failing capacitors over time a lot more easily than the Delta made models. Even Delta ones are now failing after 12 years of usage.

Btw, there are several GTX 680 models with 8-pin+6-pin power connectors, usually overclocked versions like eVGA Classified, that trigger the SMC power draw protection and need the Pixla's mod.