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Author Topic: Max GPUs with a Mac  (Read 12217 times)
sdr
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« on: June 27, 2015, 10:16:13 PM »

This topic is already often discussed and the answer so far was: 4...

A (classic) MacPro can recognize and run 4 GPUs... No!

Until today I've run my cMP with four cards (1x GTX Titan X, 1x GTX980, 2x GTX Titan) - today I wanted to tune up my system by swapping the two Titan's with two 980Ti's.

That was the idea! But reality is different - with the new configuration I wasn't able to boot my cMP, first I thought one of the cards is defective, removed one and ... system boots! I checked that card, it's fine... used one of the "old" Titan's instead, system doesn't boot... everytime I took one card out of the rig, the system boots.

I replaced the Titan X with a old Radeon (Mac) card - system doesn't boot. Every time I try to run four cards, the system refuses to boot.

Looks like the mix out of two "old" Kepler based cards and two new Maxwell based cards was the max GPU configuration, if you want to run Maxwell based cards your limit is three...

Question now is: Can this be stretched?

The reason why I am posting in this subforum, my system is/was:
- cMP 4.1/5.1
- GTX Titan X (was internal, currently it's laying next to my at my desk)
- Amfeltec GPU Cluster running the other three cards
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netkas
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« Reply #1 on: June 28, 2015, 03:54:40 PM »

I heard that issue could be caused by webdriver, but one cant run maxwell cards without webdriver.

Describe how it doesn't boot.

do you still hear boot chime ? Can you get to bootpicker (holding alt/option durring boot) if you have bootscreen. Can you boot Windows, if bootpicker works ?
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sdr
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« Reply #2 on: June 28, 2015, 05:14:55 PM »

Thats the point, the system doesn't come up - no, the system doesn't give the boot chime.

All I get is a blank black screen and a system doing nothing - same behavior I got when I tried to run 5 GPUs.
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netkas
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« Reply #3 on: June 28, 2015, 05:59:19 PM »

So, the scheme is:
Pcie slot 1 : 1 videocard
Pcie slot 2 : pcie splitter -> 3 videocards

Right ?
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sdr
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« Reply #4 on: June 28, 2015, 07:04:59 PM »

Right, that was the scheme before I swapped the Titans with the 980Ti's.

Working config was (1x GTX Titan X, 1x GTX 980, 2x GTX Titan):
PCIe slot 1: 1 videocard
PCIe slot 2: host board for the cluster -> 3 videocards

Not working, PCIe slots used as above, but instead of the 2x Titan are now 2x 980Ti's in the system.

When I uninstall one of that cards, it works.

Current config:
PCIe slot 1: empty
PCIe slot 2: host board for the cluster -> 3 videocards (2x GTX 980Ti, 1x GTX 980)

I am running the three cards at the cluster because they are all water cooled and now connected within the cooling loop.
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netkas
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« Reply #5 on: June 28, 2015, 11:23:13 PM »

So, 2 maxwell + 2 kepler - works
4 maxwells doesnt

right ?

could you try the combo of 3 maxwell + 1 kepler ?
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sdr
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« Reply #6 on: June 29, 2015, 06:10:03 PM »

Correct that works...

Tried 3 Maxwell + 1 Kepler, doesnt run
Tried also 3 Maxwell + 1 Radeon HD5770 (mac), doesn't run.

It really looks like the Maxwell cards take all... well, yes, what? From my old PC days I know that having not enough free interrupts can let you run in similar problems.
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netkas
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« Reply #7 on: June 29, 2015, 08:31:24 PM »

Interrupts, io space, dma resources, could be anything, sadly you can't boot to check that.
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registudio
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« Reply #8 on: June 29, 2015, 08:41:18 PM »

Correct that works...

Tried 3 Maxwell + 1 Kepler, doesnt run
Tried also 3 Maxwell + 1 Radeon HD5770 (mac), doesn't run.

It really looks like the Maxwell cards take all... well, yes, what? From my old PC days I know that having not enough free interrupts can let you run in similar problems.


To share my experience, I was running 1xGTX 770 4GB (internal) plus 4xGTX Titan (in Cubix) under Mac OS 10.8.5.
However now I have replaced the 770 one by a GTX Titan X under Yosemite 10.10.3 with latest nVidia web driver and only the GTX Titan X (internal) plus 2xGTX Titans are recognized in my Cubix.
I presume you are under Yosemite, correct?

Cheers
Regis
« Last Edit: June 29, 2015, 08:43:17 PM by registudio » Logged
sdr
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« Reply #9 on: June 29, 2015, 08:46:48 PM »

Interrupts, io space, dma resources, could be anything, sadly you can't boot to check that.

Well, with three cards I can boot and see what currently is used... if I would know where to look at/where I can find that information.
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sdr
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« Reply #10 on: June 29, 2015, 08:48:58 PM »

To share my experience, I was running 1xGTX 770 4GB (internal) plus 4xGTX Titan (in Cubix) under Mac OS 10.8.5.
However now I have replaced the 770 one by a GTX Titan X under Yosemite 10.10.3 with latest nVidia web driver and only the GTX Titan X (internal) plus 2xGTX Titans are recognized in my Cubix.
I presume you are under Yosemite, correct?

Cheers
Regis

Yes, I am running Yosemite - but Yosemite isn't at this point the problem as I can't even boot into any OS/I don't get the boot chime.
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