begging for help - performance in multi screen

Hi folks,

Tonight I finished mounting my extra screens, installing my extra video card and tweaking the BS config files to give me this (click for larger):

Now it is truly awesome in every way except one: it runs at 10FPS. This, with your help, I hope to fix.

So my specs are:

- Q6600 quad core 2.4GHz OC to 2.88 GHz, using all 4 cores via the dcsbsaffinitytool GUI tool

- Gigabyte P35-DS4 mobo

- 2GB G.Skill DDR2 PC8500

- 1x Gigabyte 9800 GTX+ 1GB running the left and centre screens

- 1x MSI 8800 Ultra 768MB running right and ABRIS screens

- 2x WD Raptor 10k RPM drives in RAID 0

- Vista 32

- Onboard sound *

* Note that my X-Fi PCIe soundcard stopped working when I added the second GPU today. I don't know if that is related, but I am now using onboard sound (with the unrecognised soundcard still in the slot).

Main screens run at 1280x768, the ABRIS runs at 1024x768 (non-fullscreen). This is pretty much non-negotiable, as messing with the resolutions causes problems with being able to see the multiplayer menu buttons.

This rig was pulling 13k+ in 3dmark06 before I added the 9800GTX+ and it ran BS with just the centre screen and ABRIS really well.

So I dropped the graphic details down from high, to now medium with 0 water. No difference to FPS. Any ideas? All comments appreciated.

Cheers rup

Faced with that, I think my next step would be to get that sound card situation figured out. (Either get it working [preferable], or get it out).

I'm not a multi-screen guru, but I have to wonder if bumping that 2 Gb of ram up to something higher might help. Hopefully someone else here can give you a more authoritative answer on that.

Which Operating System are you running? (and 32 bit or 64 bit?)

OS is Vista 32, sorry bout that. Updated in OP. I removed the offending sound card altogether.

OK so benchmarks showed up some very interesting results. All tested in single player instant action using FRAPS.

Running just the main screen and the ABRIS (no left/right), both screens on the 9800 card, I got 50FPS on low settings and 37 FPS on high settings.

Running just the main screen and the ABRIS (no left/right), with the main screen on the 9800 and the ABRIS on the 8800, I got 25FPS on low settings and 20 FPS on high settings!

So basically it works twice as well putting both screens on one card as it does putting one screen on each card. That doesn't make sense at all. I'd expect increased FPS as each GPU has only one screen to deal with.

Putting left and centre on the 9800 and right and ABRIS on the 8800 gives me 12 FPS low settings or 10FPS high settings.

Any ideas? It looks like some sort of inefficiency communicating with two GPUs?

Following on from the last post, I thought "maybe it just runs at the speed of the slowest card", so I ditched the left and right screens again and just ran centre/ABRIS, but this time both screens on the 8800. Guess what... 48 FPS on low.

So it really does only seem to be an issue when both cards are in use. Wtf?

You might have two GPU's, but DCS really only uses one CPU core ;)

Further, I would also guess that you're splitting the bandwidth on the PCI bus which may also be causing problems.

Appreciate the thoughts GG. If that's the case though, surely there would be an outcry by all those that thought they were going to get increased performance running two GPUs? Yet commonly accepted wisdom is that adding a 2nd GPU gives you almost but not quite double the performance. I get half the performance by adding a second GPU. In the words of the Chewbacca defence: that does not make sense.

It seems I'd be better off trying to flog my GPUs and getting a single quad-head 4850X2, but that's an expensive proposition with no guarantee of success. Surely this problem can be solved.

...and there's even a fire extinguisher in case the set-up overloads the power supply...

:eek:

...

Commonly known fact, however, is that DCS is not programmed to use multiple GPUs :)

Unfortunate, but it is how it is. Of course, I could also be wrong and the culprit may be elsewhere. Have you also tried playing with the affinity to see what effect that has?

Commonly known fact, however, is that DCS is not programmed to use multiple GPUs :)

 

Unfortunate, but it is how it is. Of course, I could also be wrong and the culprit may be elsewhere. Have you also tried playing with the affinity to see what effect that has?

Yeah, i think DCS affinity tool is an solution.

I don´t have 4 monitors, but I have 2 Monitors ans therefore using one ghost monitor on the left hand side, totalling 3840*1024 Pixels.

I have an E8650 with an 1Gbyte Radeon 4870. Before using Affinity, I got about 20 FPS over densely populated area, afterwards more than 45 FPS... :pilotfly:

It may just be too many monitors for bs to handle... :(

Maybe you can try a Triplehead2Go set up with your three screens on the first video output of your 9800, and plug the fourth screen on the second video output. Of course, you need to invest in a TH2Go which is not cheap.

There was another thread that was going on stating that not using the onboard sound resulted in a 10fps increase on some mid-range machines.

As stated in another post, Black shark is not really meant to handle multiple GPU's and in some games, SLI or multiple GPU's actually result in lower frame rates. I hope they improve the multimonitor support soon. Something else that you didn't mention is that you are most likely running in Window mode on the game instead of full screen mode which on most machines is a FPS hit.

That's one hell of a setup; hope you get it working to your satisfaction soon. Personally I wouldn't run LESS THAN 4gb ram with Vista. It will probably take another 2 years before we have the desktop hardware to run a configuration like yours. So maybe it's just a matter of time if you have the patience.

Something else that you didn't mention is that you are most likely running in Window mode on the game instead of full screen mode which on most machines is a FPS hit.

Yeah, I suspect that, too. When I tried to run BS on Vista in window mode and with only two screens (and one virtual screen of course) there was a huge performance hit, but now I run it in fullscreen on XP and there is only a marginal FPS drop.

If you have a copy of XP I would set up a dualboot environment and see if it works better then.

I'm watching this with interest..

Why in Vista would you run in Window'd mode?

Thank you all for your replies.

Yeah, i think DCS affinity tool is an solution.

OP states that I am using dcsbsaffinitytool to use all 4 cores :thumbup:

It may just be too many monitors for bs to handle... :(

That's not really the problem - post #3 describes the major issue.

Maybe you can try a Triplehead2Go ... Of course, you need to invest in a TH2Go which is not cheap.

Quite :) Maybe as a last resort, but not until I've tested the performance with a borrowed one. Anybody in Brisbane got a TH2G for me to test? :music_whistling:

You might like to pm URZE. He is the guru on multiple screens see - http://www.leftside-limited.com/

Will do so, thanks.

There was another thread that was going on stating that not using the onboard sound resulted in a 10fps increase on some mid-range machines.

 

Something else that you didn't mention is that you are most likely running in Window mode on the game instead of full screen mode which on most machines is a FPS hit.

The major issue is the major FPS hit just by introducing the second GPU. I get 50FPS on low with the onboard sound with 2 screens on 1 GPU, or 25 FPS on low with onboard sound with each GPU running one screen. Yes the overall FPS would be improved by not using windowed, but it doesn't explain the difference introduced by using a second GPU.

That's one hell of a setup; hope you get it working to your satisfaction soon. Personally I wouldn't run LESS THAN 4gb ram with Vista.

RAM is my next step. 4GB will be in there by this evening. And I hope I get it running too :)

Yeah, I suspect that, too. When I tried to run BS on Vista in window mode and with only two screens (and one virtual screen of course) there was a huge performance hit, but now I run it in fullscreen on XP and there is only a marginal FPS drop.

 

If you have a copy of XP I would set up a dualboot environment and see if it works better then.

As above I can get 50FPS out of it with two screens if I use a single GPU. XP is probably a second-last resort.

I'm watching this with interest..

 

Why in Vista would you run in Window'd mode?

'cause it don't work otherwise :)

I was not aware that 2 different “type” of Nvidia card can run 1 application on a same mobo and run independently… Not SLI since not the same card and with and Intel chipset…

ODD to say the least. My hypothesis on your slow down would be the bandwidth bridge between both cards to the cpu. It’s too limited? Was not intended for that purposes? But I’m not sure… I never saw this type of configuration before.

Anyhow, nice cockpit :D

Consider that your 32bit OS can only handle about 4Gb RAM total - this includes your GPU RAM. It's not Microsoft's fault, but rather an x86 hardware problem.

Vista SP1 recognizes more than 4Gb RAM, but doesn't actually use anything past the limitation.

So in fact, your 1GB+768MB card is already eating into the limit, add to that all your other memory mapped devices, and Vista itself (resource hog that it is), I wouldn't be surprised that you're getting abysmal fps.

EDIT: you've obviously spent some time and cash getting that setup properly - and it looks fantastic. Why not just invest a little bit more for TripleHead2go. With that setup, TH2go is a must.

I'd definitely go along with Tharos and TheMoose on this. Your two graphics cards will be fighting for bandwidth on the PCI bus and in all likelihood, generating a lot of contention resulting in their respective frame rates being hurt. SLI, Crossfire (and probably TripleHead2Go?) multi-gpu solutions work cooperatively thus avoiding this contention.

--

Murphy

OK a bit of research turned up some interesting snippets:

- My mobo disables the PCIe x1 slots when the PCIe_16_2 GPU slot is in use. That explains why my PCIe sound card stopped working. 1 mystery solved.

- While the PCIe_16_1 GPU slot supports x16, the PCIe_16_2 GPU slot only supports x4 (though it is physically an x16 slot). Maybe if I drop slot 1 to x4 (is this possible?) it might sync better?

clues.... hopes rising....

*edit*

Been trying to figure out how to limit the PCIe x16 lanes to x4 - according to this post http://www.tomshardware.com/reviews/pci-express-2-0,1915-4.html you need to tape the socket! Any better ideas before I try that?

Adding in another 4GB of G.Skill PC8500 (for a total 6GB - I know that's more than Vista32 can handle, but it shouldn't hurt right?) tonight had 2 effects:

- wouldn't boot windows with the existing OC parameters, so I'm back down to 2.4 GHz.

- boosted FPS from 10 to 15 in 4-head low detail AND it's much less stuttery.

So it seems even with 20% less CPU performance, I've still got a 50% FPS boost from the extra RAM. Plus I have at least 20% additional performance headroom with a new OC.

The hunt continues...

I think it's a CPU limit. You may get 50+ FPS with each card running two screens, but when you use 4 screens ran by two independend cards you're dividing the GPU work but doubling the CPU work because there's more to see and calculate.

Dunno though, I hope you solve it without spending too much because it seems you already did :)

OK latest:

With the added RAM and an OC to 3.2 GHz (400x8 ) I get 17FPS on medium settings plus 2xAA 2xAF with all 4 screens running. I'ts aaaalmost enjoyably playable.

I ran 3DMark06 on each of the GPUs to verify the x4 slot was holding up the 9800. Lo and behold: the 8800 Ultra (in slot 1) got 13,500 3dmarks, and the 9800 GTX+ (in slot 2) got 10,000. So yes, there is a definite bottleneck there.

Solution:

- new mobo supporting twin x16 GPU slots (this one? http://pcgogo.com.au/index.php?act=viewProd&productId=8128)

- use Asus PCIe soundcard to free up more CPU cycles

- maybe upgrade to Windows 7 64bit

With that I hope to crack the 25FPS barrier. We shall see. Thanks for the help so far.

All three things listed should help, but the most critical (and it costs you nothing to try with Win7) is the OS, second thing is the new mobo, the soundcard - don't bother, X-Fi PCIe will work as well as Asus one, under the assumption that the new mobo is able to push all the PCIe bandwidth available.