Low CPU & GPU use but low FPS?

[Blakeman 0]

Thanks guys, but my PC was built from scratch about 6 months ago. As you can tell from my CPU, I'm running an X99 motherboard, which is enthusiast grade, with 16GB of DDR4 memory. The bottleneck just can't be related to hardware.

[mdavis 10]

Are you by any chance using both UHD or HD mesh with W2XP or OSM2XP scenery?  There are a few area in Europe where my framerates drop into the 20's under massive scenery loads, even with a near-state of the art system and 32GB RAM. 

 

Also, what is your true VRAM load?  Have you installed GPU-Z and checked?  If you are over the VRAM limit of your graphics card, you'll see very low framerates.  The number in the Rendering window at the bottom is only XP textures, not total VRAM.

[tonywob 4,770]

I've seen with intensive scenery such as HD Mesh and W2XP that X-Plane will appear to struggle whilst the CPU/GPU utilisation is only around 20/30%. It would seem that this maybe some issue related to bus-speeds, as certain types of scenery which are processed by the CPU (e.g. Forests and facades) don't seem to be processed fast enough. I've tried reducing the number of triangles rendered a lot in the objects, but this made little difference. The biggest difference I have seen with performance is by reducing the density of trees and the complexity of the polygons used for forests and facades (OSM buildings).

[Slayer 190]

Possibly try dropping the PCI bus to 2.0 compatibility. Could be there is an issue with 3.0 PCI express between the motherboard and card. Long shot I know but I've seen stranger things.

[mdavis 10]

Going back to your original post, I see you're running two GTX970 cards in SLI.  X-Plane does not like SLI, so disable one of your cards, making sure the primary card is PCI 3.0 slot, not PCI 2.0.  You still have a total of 4GB of VRAM.  Also make sure your loading drive is on a SATA3 port.  Mobos with SATA3 don't have ALL ports at 3-level, some are SATA2.

[jwk34953 0]

Low framerate due mostly, possibly entirely on choice of CPU and misunderstanding how multicore CPUs work, and not understanding how X-Plane works. Turbo CPU frequency for your is 3600MHz with 1 or 2 cores only! With 3 or more cores this drops to 3400MHz due to heat dissipation causing CPU throttling.

 

X-Plane uses only 1 core for the flight model and is the greatest single hardware contribution to frame rate. All other aspects of X-Plane and handled by the other cores. Sometimes people look at the core loads and thing that the flight model is multi-threaded but it is not. What they are seeing is the flight model thread being moved from core to core, but the thread is still singular. The movement from core to core is not done by X-Plane, it is done by Windows scheduler and is done to spread heat evenly across all cores to prevent hot spots in the CPU die. I know it's often a difficult concept for many people (including myself) to understand at first but this is the way X-Plane works. The fastest CPU for X-Plane currently made is the i7-4790K, there is nothing faster at this point.

 

Low frame rate not likely with your GPU. And tests done at Anandtech show almost no difference in graphics performance whether GPU card is installed in PCI-e ver. 2.x or ver. 3.x. What does impact graphics performance is whether card is getting 16 PCI lanes, 8 PCI lanes, or 4 PCI lanes- check your manual to see how your motherboard delegates PCI-e lanes for different combinations and slot locations of add-in cards. Cards in SLI usually don't detract from frame rate, they just don't add anything and are costly. Take one video card out and any other cards you have installed for troubleshooting purposes.

 

To try to improve framerate somewhat, turn everything down to minimum settings or off, then turn each one up, one at a time, observe your framerate, turn it back down if eats too many frames. When you find a happy medium between framerate and eye candy and this will be the best you can do with your processor.

 

Bottom line fastest CPU single core speed always wins with X-Plane.

 

Check out forums.x-plane.org hardware forum for more info.

[CPT747 1]

Confirming the truth more and more : for PC-simulation;having two-core CPU with 2X6 GHz is much better in overall performance than a CPU with 8-cores !

[mdavis 10]

Yes.  Waiting for that 6GHz CPU.  I can push mine to about 5.2GHz but that's asking for trouble down the line.

[CPT747 1]

Yes. Unfortunately,the  available CPU-speed is stiil behind the FSX-speed-capability developed 2006 !

[kneighbour 32]

 

 

I have recently exchanged my GTX770 for a GTX850 and have not gained a single FPS in a controlled comparison scenario.

 

I am a bit puzzled as you why you would go to a much poorer video card and expect a gain in fps? The GTX850 is a consurmer level card and is 2 whole levels below the 770. Perhaps you meant the GTX 580?

[Janov 2,383]

I am a bit puzzled as you why you would go to a much poorer video card and expect a gain in fps? The GTX850 is a consurmer level card and is 2 whole levels below the 770. Perhaps you meant the GTX 580?

 

You are entirely right and I have no idea why I wrote that. In fact my new video card is a EVGA GTX970 with 4GB DDR5 VRAM.

 

Sorry for the confusion!

 

Jan

[JimmiG 244]

Yes.  Waiting for that 6GHz CPU.  I can push mine to about 5.2GHz but that's asking for trouble down the line.

 

Or we could hope that flight simulator developers start taking advantage of more cores like the rest of the industry already does. Taking full advantage of 8 cores OC'd to 5 GHz would be the same as a 40 GHz, single-core CPU.

[Janov 2,383]

Or we could hope that flight simulator developers start taking advantage of more cores like the rest of the industry already does. Taking full advantage of 8 cores OC'd to 5 GHz would be the same as a 40 GHz, single-core CPU.

 

This is open to debate. And Ben Supnik, lead designer of X-Plane, has posted often about that misconception in his development blog.

 

One of his favourite sayings in this context is: "Nine women can´t have a baby in one month"...

 

There is appearantly more to making the whole process faster than throwing more cores at it.

 

Jan

[FloB 34]

I think that mantle/vulkan and DX12 are excatly build for that purpose, allowing to spread the CPU related graphics workload to more than one core. That wasn't possible before, at least not with a significant performance gain.

Time will tell. But even then it won't be: double the cores, double the FPS. It never will.

 

Flo

[alpha12125 213]

I think that mantle/vulkan and DX12 are excatly build for that purpose, allowing to spread the CPU related graphics workload to more than one core. That wasn't possible before, at least not with a significant performance gain.

Time will tell. But even then it won't be: double the cores, double the FPS. It never will.

 

Flo

DirectX will never be used with X-Plane as it is Windows only. Vulcan could be a possibility but is way to early to be sure it is going to be a replacement of opengl. Laminar is changing system requirements only in complete version changes, so we wont see a change until v11 in that department. Personally i think it will be V12 before we will see any vulcan or other replacement opengl replacement technology.