Keeping multiple video cards busy

Ken g6

Programming Moderator, Elite Member
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Dec 11, 1999
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I recently got a new system (From @TennesseeTony, thanks!) with a Xeon e5-2683-v3 in a MSI X99S-SLI-PLUS board. It's getting warmer now, and the new system resides in the basement, so I decided to put both my main video cards in it, a 750ti and a 1060 3GB. The problem is, watch-ing nvidia-smi in Linux, the video cards keep dropping to near 50% usage, though sometimes they're at 100%. And the watt use is much lower than it had been. How can I keep multiple (I'm thinking of at least one more) video cards at 100% usage in one system? Or, what's causing the dropoff in performance?
 

biodoc

Diamond Member
Dec 29, 2005
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You have PCIE3.0, 40 PCIE lanes so those factors shouldn't be limiting at all. Is a 2 GHZ core fast enough to feed those GPUs? Are you reserving a full core for each GPU?
 

crashtech

Lifer
Jan 4, 2013
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That CPU should be running at an x5 Turbo bin at full load for 2.5 GHz, which is faster than 2 GHz, but still a bit slow. Verifying CPU and memory speed I suppose was not overlooked, but has to be mentioned. Are all four memory channels populated? Some projects seem to hit memory pretty hard.
 

Ken g6

Programming Moderator, Elite Member
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Dec 11, 1999
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I think I solved it. I turned off the Meltdown fix with "nopti" in /etc/default/grub, and sudo update-grub. After a reboot, the system is taking "no pity" on the GPUs. :) I'll have to rearrange them for better airflow, but they're working at 100% now.
 

Ken g6

Programming Moderator, Elite Member
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Dec 11, 1999
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The Meltdown fix destroys DC performance? :eek:
It's funny, on my Skylake with one video card, I never noticed any problem. But on this Haswell-E with two it seems it was a big problem.
 

Markfw

CPU Moderator, VC&G Moderator, Elite Member
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May 16, 2002
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I have not put the meltdown fixes on any of my DC boxes. There is nothing on them to "steal". But I have 4 2683's also, and I reserve at least one CPU for each card. ( I set the CPU% in BOINC at 85% since my video cards do F@H. In linux they are at 100% load (about).

I am slowly dumping all my Intel boxes for AMD so I don't have to worry about this anyway,. 2700X is coming Tuesday.
 

biodoc

Diamond Member
Dec 29, 2005
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With windows, how do you avoid these meltdown fixes?

My understanding is the most recent Nvidia drivers (January and later) have "fixes.

I noticed this in the driver manager on linux mint 18.3. Is this intel microcode update meltdown related?

 

Markfw

CPU Moderator, VC&G Moderator, Elite Member
Super Moderator
May 16, 2002
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With windows, how do you avoid these meltdown fixes?

My understanding is the most recent Nvidia drivers (January and later) have "fixes.

I noticed this in the driver manager on linux mint 18.3. Is this intel microcode update meltdown related?

Well, I don't do the bios fixes, and most of my boxes are linux and have been running since before meltdown with no update/reboot. The few Windows boxes will soon be all AMD.
 

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