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Overclocking performance

Posted: Sat May 04, 2019 4:37 am
by FSXDEV
Hi guys,

I’m lookin into VR flight sim for the first time since I stopped playing fsx 9 years ago. How much of a difference will Overclocking an i9900 make compared to stock? Would getting to 5.5 ghz be much of a difference over 5ghz?

Thanks

Re: Overclocking performance

Posted: Sat May 04, 2019 10:09 am
by Pete Dowson
I’m lookin into VR flight sim for the first time since I stopped playing fsx 9 years ago. How much of a difference will Overclocking an i9900 make compared to stock? Would getting to 5.5 ghz be much of a difference over 5ghz?
I don't know about VR. My system involved 3 projectors with three P3D scenery windows. My new PC is a 9900K clocked at 5.5Ghz, with the cache clocked at 5.0GHz and 3600 MHz RAM. and the difference from my previous system, a 7900X clocked to 4.8GHz with 2800 MHz RAM is dramatic.

My test scenario involves Aerosoft or UK2000 EGLL with AI traffic, and on my previous setup I was getting 18-24 fps and microstutters even with AI traffic limited to 80. On the new system I get 24-30 fps, averaging 26 or more, and smoother, even with 200 AI aircraft.

Mind you, we also changed from 2 x 1080Ti's in SLI to 2 x 2080Ti's with nVlink SLI. They probably help too.

I don't know which higher speed component is mostly responsible, probably a combination. There's always going to be a bottleneck somewhere and just overclocking the processor without looking at everything else might not gain you the improvement you'd expect. 5.0 to .5 isn't necessarily at 10% improvement in performance.

Pete

Re: Overclocking performance

Posted: Sat May 04, 2019 6:28 pm
by FSXDEV
Thanks for the info. Have you tried your setup with 1 video card vs 2? Would a better card such as titan rtx, or quadro 8000/6000 improve your system?

Re: Overclocking performance

Posted: Sat May 04, 2019 10:29 pm
by Pete Dowson
Thanks for the info. Have you tried your setup with 1 video card vs 2? Would a better card such as titan rtx, or quadro 8000/6000 improve your system?
The performance was the same with one card, but the two were a little better with smoothness.

Actually I currently thinking of changing to a cooled and overclocked RTX Titan, as its VRAM is 24Gb, more than the 2 x 11Gb on the two 2080Ti's, and of course, even though the nVlink SLI strap is fast, it's still another data path slowing things down.

Pete

Re: Overclocking performance

Posted: Wed May 08, 2019 11:50 am
by francescodoenz
9900k at 5.5GHz is amazing! What Vcore and cooling are you using??

Re: Overclocking performance

Posted: Wed May 08, 2019 3:22 pm
by AnkH
Do the maths, pretty simple. Clocking from 5.0 to 5.5GHz results in 10% more clock speed and in the unrealistic situation of 10% performance increase, you will get 10% more FPS. Means: if you get now 20FPS, you will afterwards get 22FPS. Worth the hassle? I would say no, it will certainly not make the difference between playable or non-usable simulator and it will certainly not allow VR if stock is not enough.

Don't be fooled by the example of Pete, he sees the nice performance increase not only due to the increased clock rates. He has changed more:

- a solid + 15% increase in clock rates
- change to GPUs that provide 30-50% more power.
- a solid 28% increase in RAM bandwith

Regarding this system change, his increase in FPS of about 25-30% looks dramatic, but it is pretty much in line of the improved hardware he uses now.

Re: Overclocking performance

Posted: Wed May 08, 2019 4:03 pm
by Pete Dowson
9900k at 5.5GHz is amazing! What Vcore and cooling are you using??

I don't recall the vCore off-hand. Not as high as you'd expect. The cooler is the important part -- an external Koolance cooier which is probably itself about a third the size of the full case of the main PC. It has to be switched on 10-20 minutes before the PC else it that often BSOD on booting into Windows, if not soon after.

But as Chris said, it isn't only the CPU. The cache at 5.0 has a lot to do with it, as does the faster RAM. And I've tried to optimise the spread of the 8 core usages across the add-on processes I have to run to support my cockpit system.

Even so, Core 0 is still hitting 100% most of the time -- but that's probably because i run with about 3 times the number of AI as before -- over 200 and up to 300 in busy areas, up from my previous limit of 80.

I plan to limit it again, to 200 or even only 150 so I can ramp up some other things. i'd really like to use Orbs True earth series, but no way that will work well even with this beast.

It's having the three scenery views for ny 210 FOV screen which is the real killer, and the reason for having this monster built! ;-)

Pete