Why am I getting poor performance with 4 graphics cards?

[Frequent_Flyer 1]

 

28 minutes ago, ZLA Steve said:

This post headline initially made me chuckle.

 

It made me think of this analogy.

Your 4 graphics cards are the Autobahn, where speed limits in many places are non existent, ergo, you can go as fast as you want.

 

P3D is your 1992 VW rabbit. 4-cylinder 1.8 litre 4-speed rocketship that tops out at 120kph.

Try as you might, you are never going to reach the top speed you imagine in that car despite having all the space in the world to do so. Old engine, old limits...

 

 

As many others have said, it's far better to upgrade the 4 old cards to one current gen card with as much VRAM as possible.

Happy motorin' 😉

 

34 minutes ago, bgpearce01 said:

I have yet to see a mainstream motherboard use 3 X 16 pci lanes(at the same time).  Once you go past two you will need to cut them down to 8.  The architecture itself is limited to 64 lanes and you need to keep some open for data i/0 etc.  Regardless this is hardly a bottleneck in this situation.  You could probably pull a card and see the same if not better performance using 2.

 

Regarding using 3 or 4 video cards.  Starting with the pascal series cards (1070, 1080 etc), nvidia is restricting the use of more than 2 cards in sli.  The return and complexity of drivers after 2 cards is just not worth it.  I wanted to mention this incase anyone was thinking of adding a third or fourth card.  It would be a total waste of money and even if it did work in P3D, it wont in anything else such as games.  If you are running older 9 series of even 7 series nvidia cards, sure you could theoretically run 3 or 4.  But 2X gtx 1080 ti's will beat ANY 3 or 4 card variations.  Not to mention vram is not pooled so as you decrease the vram you will start to see stutters.

 The graphics cards are not SLI'd. There is a specific use for each of the graphics cards, due to the fact that I have 4 projectors.  I have 11 displays overall. There is a reason I chose the Autobahn :).

[bgpearce01 36]

1 minute ago, Frequent_Flyer said:

 The graphics cards are not SLI'd. There is a specific use for each of the graphics cards, due to the fact that I have 4 projectors.  I have 11 displays overall. There is a reason I chose the Autobahn :).

😲

[DylanM 1,069]

30 minutes ago, Frequent_Flyer said:

The graphics cards are not SLI'd. There is a specific use for each of the graphics cards, due to the fact that I have 4 projectors.  I have 11 displays overall. There is a reason I chose the Autobahn :).

Your ingenuity / insanity is an inspiration to us all... 😉

I really do hope you get your performance issues sorted, and post up some pictures of your setup!

 

[Chock 17,769]

58 minutes ago, ZLA Steve said:

P3D is your 1992 VW rabbit. 4-cylinder 1.8 litre 4-speed rocketship that tops out at 120kph.

Not that it was your point of course, but there's no such thing as a 1992 VW Rabbit. Only Mark I and Mark V variants of the VW Golf were badged in the US and Canada as the Rabbit. The Mark II was made from '83 until '91 and was always the Golf, even in the US/Canada, as was the Mark III, which was made from '91 until '97 and the Mark IV from '97-'03, and the Mark V was '03-'08, but not marketed in the US or Canada until '06; so you could only have a VW Rabbit dating from either '74-'82 or '06-'08. The 1.8 Mark I Golf (aka the Rabbit in the US) could do 180 km/h too, it was the 1.1 that were slow, but even those could still manage 145 km/h . 🙂

[kurtb 121]

😂lol - i love it

[whitav8 98]

You would be much better off with as few high end (1080ti) as possible Nvidia (or AMD with Eyefinity) graphics cards as possible since 4 separate cards just provide more monitor ports and little acceleration of the graphics - nothing really is done in parallel - just one monitor after another is being processed in the serial list of the graphics pipeline. Maybe some of the graphics are just the out the window scenes and that should get the fastest video card - maybe three monitors worth? As the others have said, you need the latest CPU running at 5 Ghz with fast memory (>3000) and an SSD disk. Forget SLI anyway.

 

[ZLA Steve 370]

6 hours ago, Chock said:

Not that it was your point of course, but there's no such thing as a 1992 VW Rabbit. Only Mark I and Mark V variants of the VW Golf were badged in the US and Canada as the Rabbit. The Mark II was made from '83 until '91 and was always the Golf, even in the US/Canada, as was the Mark III, which was made from '91 until '97 and the Mark IV from '97-'03, and the Mark V was '03-'08, but not marketed in the US or Canada until '06; so you could only have a VW Rabbit dating from either '74-'82 or '06-'08. The 1.8 Mark I Golf (aka the Rabbit in the US) could do 180 km/h too, it was the 1.1 that were slow, but even those could still manage 145 km/h . 🙂

When a light joke goes too far... 😉

FWIW, I owned an '87 GTI that would do every bit of 145 mph on the autobahn, much to the dismay of my then girlfriend.

[G-RFRY 1,710]

All PCI slot are 16/8 lanes when one slot is used it runs at 16 when the motherboard detects two 2 GPUs each PCI auto switches to 8 giving a total 2x8=16, and their are some that run 4x4=16 using four slots on some older boards.   

[Pete Dowson 558]

15 hours ago, Frequent_Flyer said:

Each projector of mine has its own card just like yours, so hopefully that is the best set up.

No, that's what I intended, but it was very stuttery like that. Much smoother with them all on the one card and with 3-way SLI.

15 hours ago, Frequent_Flyer said:

I take smoothness to be the opposite of having stutter.  However, from previous comments, stutter was said to have been a direct result of the CPU and not the GPU. But in your case, you say that having each projector on its own card (GPU) makes it more smooth for you. 

No, I said the opposite of that! Yes, smoothness as the absense of any stutter.

This is the part of my post you seem to hgave read wrongly, quoted with bold emphasis:

15 hours ago, Frequent_Flyer said:

Certainly the performance, frame-rate wise, isn't any better with the 3 linked up, but it is smoother than with just the one card in use and no SLI. And it is certainly much smoother than with each projector on its own card.

On your other point:

15 hours ago, Frequent_Flyer said:

However, from previous comments, stutter was said to have been a direct result of the CPU and not the GPU.

Yes, and certainly with underloaded GPUs as in my case that is true. I don't know why having each projector on its own GPU was stuttery. I can only assume it gives more work to the CPU in organising what goes where, whereas with SLI that's left to the video system.

My screen is a curved 210 degree FOV from NatVis, using their Tru-View software to undistort the image and blend overlaps perfectly. The software and its process has no affect on performance at all, as I have proven by testing without it.

I have an ordinary monitor also connected which I use for doing settings etc, as I simply cannot do anything on a curved distorted Windows image. I can't even find the mouse pointer usually! 😉

Pete

 

[Pete Dowson 558]

9 hours ago, whitav8 said:

Forget SLI anyway.

Well, without the 3-way SLI on my setup there's certainly more stutters than with it! So something doesn't add-up in all these statements that SLI doesn't work with P3D4 and that 3-way isn't supported! You are welcome to visit my humble abode and see the difference for yourself!

Agreed that frame rates are no better with SLI. No worse either.

Pete

 

[GSalden 4,656]

19 minutes ago, Pete Dowson said:

Well, without the 3-way SLI on my setup there's certainly more stutters than with it! So something doesn't add-up in all these statements that SLI doesn't work with P3D4 and that 3-way isn't supported! You are welcome to visit my humble abode and see the difference for yourself!

Agreed that frame rates are no better with SLI. No worse either.

Pete

 

Thanks voor the info Pete.

Currently I have connected 3 screens to 1 1080 Ti and everything that adds smoothness is very welcome.

I have to add that my GPU load is always 50-80% ( overclocked ) , so I am wondering If an extra card in SLI would help.

May I ask you how the GPU load was before SLI ?

thanks, Gerard

[AnkH 2,262]

1 hour ago, Pete Dowson said:

Well, without the 3-way SLI on my setup there's certainly more stutters than with it! 

May I ask what GPUs you use?

[Pete Dowson 558]

2 hours ago, GSalden said:

I have to add that my GPU load is always 50-80% ( overclocked ) , so I am wondering If an extra card in SLI would help.

Wow! What's the CPU loading? My Core 0 is at 100% for dense complex situations, less elsewhere -- perhaps 60-80. But the three GPUs never seem to get much above 20% I wish I could move more of the load onto the GPUs, but that needs big changes in P3D I think.

If your GPU is not peaking at 100% then I don't see how that's limiting P3D performance or smoothness. Of course, if at 80% it is getting hot then that might cause it to throttle somewhat I suppose. (I'm not a hardware guru -- far from it!).

2 hours ago, GSalden said:

May I ask you how the GPU load was before SLI ?

Sorry, I don't think we measured it. We just compared what happened without SLI to after we connected the GPUs and enabled it.

1 hour ago, AnkH said:

May I ask what GPUs you use?

1080Ti's, pre-overclocked by the makers. I don't remember the actual make/model. I remember that we wanted all three projectors on the same type of connection as we had sync difficulties when they were on different ones. They are all on Display Ports. (The control/boot monitor is on DVI).

Pete

 

Edited June 22, 2018 by Pete Dowson

[GSalden 4,656]

My core 0 is at dense scenery always 100%. My GPU max 80%..

[bean_sprout 1,201]

2 1070's in SLI increases smoothness on my OC'd 7700k rig.  Just 1 is usable but not enjoyable.

 

Cheers
bs