FSX, CPU & GPU discussion

[Maurice]

I know that the common thinking about FSX is that FSX is mostly CPU intensive and that the graphics card is not all that important for performance. Now, if by performance one means frames per second, then this thinking is absolutely correct especially for anyone using one projector or one monitor with a single FSX window.

But there is a huge difference once you go with multiple displays or projectors with multiple undocked windows, each one of them consuming CPU & GPU resources.

When I built my system, I decided to go for the most power I could afford and my system consists of the following:
I7 -980 CPU overclocked to 4.7 Ghz & self contained water cooled system.
Fastest 6GB (3x2Gb) memory I could find at the time (forgot what type)
GTX 480 video card
240 GB OCZ Revo drive X2 PCI Express Solid State drive
80 GB OCZ Sata II SSD drive
1200W Power supply.

Will all this, I was totally stunned that I could only achieve an average of about 20 fps at most large busy airports with 25% airline traffic, and no car traffic at all. But it really does make some sense since I am using 3 undocked windows and the CPU has to process 3 times as much scenery as it would with one view only.

Having said that, my sim is perfectly flyable and the visuals are quite smooth except perhaps when turning too fast while taxiing. Once airborne of course, frame rates are no longer an issue except if flying into severe weather or thunderstorms (not advisable at the best of time). Even then, I find the visuals quite acceptable with only minor disturbances.

Which brings me to the main point I am trying to make here. The graphics card is absolutely just about as important as the CPU in multiple views environments. Even if I was able to overclock my CPU to 10 Ghz, the GPU would not be able to process all the data sent by the CPU and I would end up with horrible visuals.

And I think the proof of this is that in my system, my graphics card shows almost 100% utilization most of the time. If I try to use the famous tweak Usepools=0, I get several additional fps, but the visuals get much worse with all kinds of spikes & white flashes since the GPU can no longer keep up with what the CPU is pumping out.

So, my conclusion is that overclocking the CPU only helps until you overpower the GPU and then it makes things much worse. If you are building a system with multiple undocked windows, I strongly suggest you pay as much attention to the GPU as you do to the CPU and that you get the most powerful & fastest video card you can afford since it will ultimately become the bottleneck.

Right now, I am happy with my current visuals since they work quite well under most normal airliner flying conditions i.e. standard rate turns & not pushing 9g in the turns. But if you fly smaller aerobatic planes in particular and do wild manoeuvres, good luck trying to get smooth graphics with multiple undocked views.

Having said all that, I don't consider myself anything even remotely close to an expert when it comes to tuning a system for optimal FSX performance, so it could very well be I screwed up something somewhere and that is why I am not getting a better performance like some of the other claims I have heard. But until proven otherwise, I stand by my statement that the GPU is just as important as the CPU in multiple views setups.

Maurice

[bussgarfield]

Interesting topic Maurice and I have to agree with you.

You are lucky to have a reasonably 'high end' computer set up and to hear that you are having a few scenery/visual hic-ups doesn't bode well for any one considering upgrading their system.

For anyone using just the one or even two monitors to include some un-docked instruments will be ok and this is probably how most simmers would be happy to operate - but then add even more monitors and we are on the downward slope.

To be fair to MS with their FS9 and FSX software, they were not intended to satisfy the likes of us wishing to build our own cockpits with dedicated boards, plugins and visuals - all of which sap the strength out of any system.

I was keen to see how the PMDG NGX operated on my three year old system sporting a 'whopping' 3.7GHz CPU, 8GB of ram and three Nvidia 9800GT GPU's each with 512mb memory. I have 3 x22" monitors for outside visuals and 3 x19" monitors in my MIP (FO not connected yet) and a CDU ready to be connected once I get the NGX sioc script from Opencockpits.

Prior to it's release the PMDG crew and beta testers said that despite the intensive nature of the product, we (the simming world) would not notice any drop in fps and in fact they could actually be increased. They may well be correct if using one monitor but my little system is indeed struggling on the ground with just the default airports and scenery. I haven't dared yet to install all my photographic UK scenery or world airports.

The NGX is a great piece of software and I am not knocking it one bit but it does seem to uphold your line of thinking when it comes to multiple monitors.

I cannot afford (or justify to the good lady) to upgrade my system just yet but even if I could, would it be really worth it in the long term ?

Perhaps multiple PC's is the way to go. One dedicated to scenery, one to FSX, one to run the cockpit lighting, one to make the coffee - now I am being silly - aren't I ?

Gary   

[ivar hestnes]

The usepool trick is not advisable when running undocked views. But the rejectthreshold trick defines a load limit that you apply to the gfx card, and that works fine on my setup. I think the more memory the better on the gfx card. I have 2gb ram on my computer, but drooling about the gtx-590 which has 3gb and it would eliminate the th2go also.

I also have the NGX installed on my computer with three screens, but I cant say that I have noticed any fps reduction. It runs just as good as the default 737, or better...

[hexpope]

I totally agree with you Maurice about the GPU when you use multiple displays. You need  a good one that can render what ever high resolution you need. If you just a one monitor setup for FSX then yes, a simple cheap card would do the trick nicely.

[Maurice]

. But the rejectthreshold trick defines a load limit that you apply to the gfx card, and that works fine on my setup. I think the more memory the better on the gfx card. I have 2gb ram on my computer, but drooling about the gtx-590 which has 3gb and it would eliminate the th2go also.

I haven't played with the rejectthreshold and I don't know what it does. Just for curiosity, what value did you set yours at?

As for the GTX 590, I did not know it would eliminate the TripleHead. Will need to talk to my wife about that 

Honey.....do we really need to buy food this month? 

Maurice

[bussgarfield]

The usepool trick is not advisable when running undocked views. But the rejectthreshold trick defines a load limit that you apply to the gfx card, and that works fine on my setup. I think the more memory the better on the gfx card. I have 2gb ram on my computer, but drooling about the gtx-590 which has 3gb and it would eliminate the th2go also.

I also have the NGX installed on my computer with three screens, but I cant say that I have noticed any fps reduction. It runs just as good as the default 737, or better...

Thats interesting Ivar as I could use the default 737 without any problems.
I forgot to mention that I have recently purchased and installed TH2Go which frees up two of my GPU's for the MIP monitors.

What please is the rejectthreshold trick ?

Gary

[hexpope]

Given that this topic is (FSX, CPU & GPU discussion) I am going to ask the question about USB monitors. I am looking to get my hands on one for the second PFD for the G1000. I know they are not good with 3D graphics, but what about using them for 2D panels that you undock from the SIM? I have read up on display Link tech and I notice that it uses the CPU from rendering the graphics etc. Now I do have a true 6 core CPU from AMD OC'ed to 4.0GHZ and I know that FSX is only using 1-3 of them which leads me to have idle on the other cores.

What I want to know is does anyone here use USB monitors in their cockpits ? I have seen DCS Blackshark builders and DCS A10 cockpit builders on youtube and it looks perfect without any lag etc.

Any suggestions would be great.

[blueskydriver]

Here is something I turned off, as AutoGen is the biggest killer in frame rates for FSX.

//TERRAIN_MAX_AUTOGEN_TREES_PER_CELL=450 //was off and at 4500
//TERRAIN_MAX_AUTOGEN_BUILDINGS_PER_CELL=3000 //off

In other words, just but the two slashes in front of these two entries your FSX.cfg file.

Of course you will not see many trees or houses, but do you need to see them in a B737? For me, the answer is no. I only care about the airport, the weather, and the ground from above FL350 or above. If you're in a GA slow and low flying then yes, because the AutoGen would be slower by the default; therefore, the CPU/GPU can keep up with the slower speed of rendering it.

I just wish there was a way to do away with the undocked views and only use one view, but somehow apply a stretch and curve to the video ouptut from that single view from the FSX computer. It could be software or hardware, but at least something. Yes, that sounds like getting men back to the moon or a monkey to Mars (because men will never go); however, there has to be a method somewhere or somehow. Of course there is the 3 FSX machines Sol 7 approach, but multiply your FSX computer costs and everything that goes with it times 3... It would've been possible until my mistress, Mrs Simlady decided to go crotch rocket...uh, F16 sim building...lol. Oh well, I am not complaining because it is much better than the alternative...

BSD

[blueskydriver]

Here is a link that deals with Buffer Pools and the RejectThreshold Ivar speaks of:

http://www.sim-outhouse.com/sohforums/showthread.php?44197-RejectThreshold-Tweak-Replacement-for-No-BufferPool

Do note that the thread is from 2010 and that is a long time ago in CPU time frames; however, the topic of the RejectThreshold is there. You can read the other responses within in the thread and they may or may not help your setup...

BSD

[Maurice]

Here is something I turned off, as AutoGen is the biggest killer in frame rates for FSX.

//TERRAIN_MAX_AUTOGEN_TREES_PER_CELL=450 //was off and at 4500
//TERRAIN_MAX_AUTOGEN_BUILDINGS_PER_CELL=3000 //off

In other words, just but the two slashes in front of these two entries your FSX.cfg file.

Isn't that exactly the same as turning the Autogen off in the display settings? But anyway, I can do with fewer trees perhaps, but fewer or no houses kills the looks of scenery such as Approaching Innsbruck for instance. I turned the autogen off and I did not like what I saw at all.

I get what you are saying but that is just a personal choice/compromise everyone needs to make based on how your system performs.

Maurice

[ivar hestnes]

I have my reject threshold set at 126976. Works very stable on my setup.

This is mentioned in my tutorial also. If anyone need it, just send me an email via the email button on my website.

@Gary
It looks like it is very random who get good or bad framerates with the NGX. Personally, I believe the more tweaks you do the worse it gets. My setup works really great 

[hexpope]

This is what I use and it works perfectly for me everytime. I don't know if I posted this before but its gold to me. Its an online service. You upload your FSX.cfg pick your system spec's from the drop down fields and let it do the rest.

Tweaking and Tuning tool for (FSX SP2/Accel - ESP/Prepar3D) Version 1.0.7 (last change 12/8/2010 6:25PM EST)

http://www.venetubo.com/fsx.html

Also if you want to see how much VRAM is being used and lots of other information regarding your card while on load I use GPU-Z it's freeware and very good to see if your spiking your VRAM and other limits with your graphics cards.

http://www.techpowerup.com/downloads/SysInfo/GPU-Z/

[blueskydriver]

Maurice,

You speak of Autogen, I forgot to mention another reason for turning it down/off is that I use FS Altitude Western and Eastern Photo Scenery, so Autogen is not needed. Even though FS Altitude is summer scenery only, you can use it anytime. Heck with this early summer we're having (70-80 temps in Wisconsin it's summer for us), I turned it on already.

The biggest thing about FS Altitude is it looks amazing from 10,000 and above. With it being photo real and adding in REX, GEX, UTX, UT, AS2012, and FS Genesis it is just one gate away from sitting next to a real plane. Although, the uniforms have not arrived...yet! At least I have a flight attendant that brings "GOOD" in flight meals...uh, no wait...nevermind, she ran off to join the crotch rocket fly boys in her F16. Okay, so it's not as real as I hoped...lol.

BSD

[Maurice]

Maurice,

You speak of Autogen, I forgot to mention another reason for turning it down/off is that I use FS Altitude Western and Eastern Photo Scenery, so Autogen is not needed.

I still don't agree BSD. I installed FSAltitude Europe a couple of years ago and I removed it because I did not like to see big patches of snow on the ground in the middle of the summer.

I still think that lower level scenery is more important than upper level scenery since most of it is often obscured by haze anyway. But when you take off & land, killing the autogen makes everything look pretty drab & lifeless. Photo scenery is better in any case since you see it at low & high altitudes although it is also summer scenery (OK of course if you only fly in semi tropical or tropical country)

So, I'll stick with autogen. But, to each their own of course and if you like FSAltitude, then you are absolutely right 

Maurice