Cores or CPU speed

Any issues, problems or troubleshooting topics related to computer hardware and the Prepar3D client application
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Cores or CPU speed

Postby BRADRCFII » Tue May 22, 2018 3:45 pm

I have been out of flight simming for a couple of years. I am planning on a new computer build using an I7 CPU. With so many CPU options available, I am wondering if the number of cores or CPU speed is more important to run the 64 bit Prepar3D? I noticed that the CPU's with more cores usually have clock speeds that are slower.

Does Prepar3d take full advantage of more than four cores?



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Re: Cores or CPU speed

Postby downscc » Wed May 23, 2018 2:37 pm

I've not noticed speed and number or cores correlation, my six-core 8700K runs a stock 4GHz with stock Tubo mode of 4.7GHz. There is a correlation between number of cores and heat, which is obvious when you think about it. I could push my four-core 6700K a little harder than the 8700K given the same cooling, but the difference in P3D performance was not measurable.

P3Dv4 does a good job of loading all six of my 8700K, and I find performance is better with HT off although this will have arguments on both sides. Don't forget your GPU, no need to get the biggest and fastest CPU unless you have lots of GPU processing power.
Dan Downs

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Rob Ainscough
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Re: Cores or CPU speed

Postby Rob Ainscough » Wed May 23, 2018 5:18 pm

I've not seen much benefit beyond 8 cores but it also depends on what add-ons you run and if you run those add-ons from the same FS PC that runs P3D.

My 10c/20t 7900X works well at 5Ghz but I disable HT to reduce heat and increase stability and P3D seems to perform better with HT OFF. You can also stagger the core frequencies, whatever core you use for primary (main synch core) allocate to a higher frequency that the other cores. This also helps reduce thread contention. Be careful with Turbo Boost Max 3.0 usage, early EFI/BIOS and drivers would trigger race conditions in several cores resulting in very poor performance which presents itself as "blurries" in P3D.

Best "bang for the buck" is the 8700K. But if you use add-ons like F1 GTN 750, MJC Q400, HiFi AS4 that can operate on separate cores then have a few extra cores can help with processing those add-ons.

Cheers, Rob.
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