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PCem performance issues with Ryzen 7 5800X System

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First post, by Narktor

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CPU Ryzen 7 5800X
RAM DDR4 3600Mhz (XMP1 Profile in Bios)
Mobo Gigabyte X570S AORUS MASTER
GPU Asus RTX 3080
OS Windows 10 Professional

Few weeks ago I setup my PCem V17 with a 233Mhz Pentium II machine. Everything worked just fine, installed games like Silver, Thief, Desperados. Everything was fine.

Then 2 days ago I start the emulator and all of a sudden the emulation speeds go south. Had to trim it back to 150Mhz to get usable results.

On Reddit someone said he uses Ryzen 9 5950X and can go up to 333Mhz without issues.
On my i7 system I can also flawlessly emulate a pentium II with 300Mhz.

But my main system is this one and it just doesnt work anymore Oo
I dont understand why, the CPU should be powerful enough shouldnt it? The i7 is even "worse" in single core tasks and PCem utilizes just one core. Still, the i7 System works perfectly fine while my AMD Zen2 system over here all of a sudden goes bonkers.

Am I missing something?
I read that when using powerful CPUs in emulation and you have low CPU usage tasks the emulation speed goes down.
So only use CPUs just fine with the workload ahead.
On my i7 System, this doesnt hold true, in idle or "low requirements" games it still works pretty fine.
On my Ryzen 7 System over here though, when going into the game, the performance worsens a lot if im on one of the "top end" CPUs at 233mhz+.

I also dont understand how this came so suddenly. Could it be tied to a windows update?
Do I need to do something in my BIOS? I actually activated CPU virtualization already in BIOS/UEFI but it didnt have any effect.

im really desperate about this problem ^^ I want to play these old games but I cant figure how to deal with this, and its not easy these days to find a place to turn to, especially since the official forums have been taken down by Sarah Parker herself xD

Can someone help me?

Btw. If I try to run PCem on my i7 system and use remoteDesktop from my main machine to use it remotely, everything works fine so far except that inside PCem, the mouse teleports/glitches around.
I read somewhere that in virtualization, activating or intensifying hardware acceleration might help with this problem, but PCem doesnt natively support such options as far as I can see and I dont know any workarounds which could help here ^^ If someone has an idea though, Id be happy if youd share it <3 😀

Reply 1 of 11, by SortingHat

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"I also dont understand how this came so suddenly. Could it be tied to a windows update?" Keywords right there bud. Microsoft has technically been 'Nokia' since Windows 8 when they fired all their PC people and replaced them with phone people form the fold up of Nokia phones. Microsoft in a leverage buyout replaced all or most of their workers.

Windows Updates now breaks most things because they only understand how to make things work for apps and phone stuff like Skype,etc. And that's on their best days! The Xbox department is ran separately by Phil Spencer and it was also broken until he fixed a bunch of things to make Xbox usable when the Xbone first came it was the 'Broken Box' essentially and now is very usable.
've had to redo PCEM OS's sometimes after a Windows update so I've learned to make a backup copy I can restore to so I at least won't lose EVERYTHING when it DOES happen. I

gave up with Launchbox because it would frequently not open whenever Windows did a major update so I emulate stand alone now which is a major pain but better then broken frontends and missing roms,etc.

Reply 2 of 11, by xenaretos

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Well, first thing I'd try is to set the CPU affinity in the task manager to even-numbered cpus only to make sure PCem doesn't get assigned secondary threads, which can happen on rare occasions and does wreck the performance. By the way, it uses up to 4 threads if you are using a 3dfx card: 1 for the CPU, 1 for GPU queueing (don't remember the exact term) and 1 for each TMU. And some of those GPU threads are indeed quite demanding.

And with this system you should probably be able to emulate 300-450 Mhz Pentium II depending on the (I can get about 350 in games with a 5600x except for Deus Ex which is only 100% stable at 266 - and this is a below average result, according to other forum posts I've read).

Reply 3 of 11, by leileilol

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The TMUs don't get threads. Splitting 3dfx into more threads just renders more of the lines in parallel. A ryzen might be fine with 4.

CPU and sound emulation share the same one thread, then the video (host video) gets a thread, and then secondary video if enabled (3dfx, 1 to 4 threads, SLI can double this to 2-8)

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long live PCem

Reply 4 of 11, by xenaretos

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Thanks for the clarification, I was too lazy to check the remnants of information that lingered in my memory. I do remember, though, that even Voodoo 1 on a Ryzen 5600x needs 2 threads to reach full performance in GPU-heavy scenarios (although the difference is just a few percent).

Reply 5 of 11, by Narktor

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I fixed the cpu affinity to core 15 (or 16) and ran my PCem with 233Mhz and started SILVER.
I opened the ressourcemonitor alongside, see screenshot here:
https://imgur.com/V1t8i7N

As you can see, CoreLoad is at 10%. Still, the emulation sits at roughly 60%, very sluggish performance.
CPU Temps are fine.

I benched my CPU with CPU-Z results are here:
https://imgur.com/SlrdJhx

Also used UserBenchmark, results are here in PDF Format:
https://www.file-upload.net/download-14738376 … chmark.pdf.html

Reply 6 of 11, by xenaretos

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Core 15 should be a secondary thread. The primary threads are 0-2-4-6-8-10-12-14 on a 8/16 CPU. And you probably want at least 4 threads assigned to PCem. Setting it to high priority might also help, although it shouldn't be that significant.

Reply 7 of 11, by Narktor

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Found the issue.
Guess what.

Energysaving options...

CPU wouldnt go to full load because it was set to energy saving after the last update.
Great! 3 days and 10hours of work for Microsoft f*cking things up 😜

Thanks for the help though, greatly appreciated! 😀

Reply 8 of 11, by DosFreak

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I still to this day experience issues with various systems and power management screwing things up. It's been a pain since it started and it looks like issues will never end.
Think the only way it will get solved if it's made a requirement and devs implement on their own systems and test instead of always running everything at full tilt 100% of the time.

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Reply 9 of 11, by Tertz

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DosFreak wrote on 2021-11-04, 15:50:

I still to this day experience issues with various systems and power management screwing things up. It's been a pain since it started and it looks like issues will never end.

I remember problems with energy saving on Core2Duo. Though, it could be the only case.
Was used new 8-bit computer emulator and it strangely worked slower than should. I've noticed this goes from CPU's "speed step" which made the frequency 50%.
The details seems were so. When the emulator started it evaluated CPU's speed when it was at full frequency. But when being in the emulator the CPU relaxed and reduced the frequency to 50%, so the emulation speed droped below the needed.
I've solved the problem by running additional background process to make the CPU keeping 100% frequency.

DOSBox CPU Benchmark
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Reply 10 of 11, by daerlnaxe

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Hi,
Same on my i7 4770k oc to 4.4ghz+ some games are ok at 200Mhz, others not and i must use a lower emulated cpu. I don't talk about only the frequency but to have a good sound with an emulation at 98% min.
I used QEMU it's far more efficient in compareason.