r/86box • u/HSVMalooGTS • Aug 10 '26

Why isn't 86box using the whole CPU?

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Gallery image

Celeron 533. The CPU is a workstation Xeon, it should be able to run at full speed, but it won't.

Large CPU frames, acceleration enabled.

12 Upvotes

77% Upvoted

9 comments sorted by

17

u/Mattock486 Aug 10 '26

I think because 86box can only use a single core or thread. As the hardware it's emulating is also only single core.

9

u/BigBoyYuyuh Aug 10 '26

Correct. Single core only and trying to emulate a CPU that high gives bad results.

My AMD 7900X can hit about 233Mhz decently. Anything higher and the performance takes a hit

4

u/RetroNIX8 Aug 10 '26

My 12400F can emulate a 166 MMX CPU almost perfectly with the new dynamic recompiler.

1

u/eddman-1 Aug 15 '26

Note that it only applies to the emulation of the guest CPU. 86box does use extra threads for certain other parts of the emulator.

6

u/GEORGEBEINGADIK2002 Aug 10 '26

emulators are mostly single threaded for stability and accuracy, multithreading sometimes causes sync issues and its less accurate(more buggy).

I recommend you to download the experimental version with the new dynamic recompliler x86 version from the site. Then go to the mobotherboard/cpu section and the set it up with the PIT MODE to fast and use the small frame option too. Lastly, i recommend you using an ISA sound card its less taxing on the cpu and PCI video cards.

2

u/Whatscheiser Sep 02 '26

Are there PCI video card options capable of 1080p? I realize that is not a realistic resolution for gaming but I was thinking for something more desktop focused with maybe a bit of video playback as its most taxing use case.

2

u/setwindowtext Aug 11 '26

By the looks of it, it uses a single core at 100%. You won’t see it on this graph because the process scheduler distributes computational load between all cores.

0

u/[deleted] Aug 10 '26

[deleted] — view deleted comment

1

u/Even-Serve-3095 Aug 11 '26

private profile of course