I made some more measurements.
90mV ripple on +5V rail (measured on decoupling caps near CPU socket) hence no recapping needed.
Removing second 32MB SIMM doesn't affect FPS in Quake. Either it fits in lower 32MB or 256kB of WB cache is enough for 64MB.
These SIMMs are same model and same year but one of them is more stable @50MHz FSB than another. Looks like I'm trying to push their limit.
Board freezes right after POST @60MHz FSB no matter what SIMM I use. Probabbly I just don't have fast enough ones.
3x50 is still noticeable faster than 4x40.
4x50 doesn't start at all @+3.45V.

When on the border of stability with very fast timings at high FSB, having only one memory module installed is preferred to two modules, irrespective of how much total RAM is installed.

If you are unable to POST at 60 MHz FSB, even with slow wait states, e.g. 2ws/2ws EDO and 3-2-3 SRAM, then try higher voltage to the CPU. I have two LSD boards and both can do 2x60 and 3x60 MHz, but it requires some trial and error. From my experience, 60 MHz needs 4 V to the CPU.

froller wrote on 2024-03-11, 12:58:

I made some more measurements. 90mV ripple on +5V rail (measured on decoupling caps near CPU socket) hence no recapping needed. […]
Show full quote

I made some more measurements.
90mV ripple on +5V rail (measured on decoupling caps near CPU socket) hence no recapping needed.
Removing second 32MB SIMM doesn't affect FPS in Quake. Either it fits in lower 32MB or 256kB of WB cache is enough for 64MB.
These SIMMs are same model and same year but one of them is more stable @50MHz FSB than another. Looks like I'm trying to push their limit.
Board freezes right after POST @60MHz FSB no matter what SIMM I use. Probabbly I just don't have fast enough ones.
3x50 is still noticeable faster than 4x40.
4x50 doesn't start at all @+3.45V.

According to your screenshot, you use WB and 8bits for TAG RAM. Yes, that is sufficient for 64MB cacheable area.
But it is not a good setting performance wise.
Therefore I suggest to use either WT (then cacheable area is 64MB)
or WB, but tag ram 7bits (then the cacheable area is only 32MB with 256kb of cache).
I assume with both settings, you get higher values. Do not forget to reduce the RAM with WB and 7 bit.
When you have managed to get better values, you can re-run the comparison between 150 and 160MHz.

pshipkov wrote on 2022-05-07, 04:25:

https://www.petershipkov.com/temp/retro_pc_images/benchmarks/486_ls-486e_rev_d_q1_200_2-1-2.png A video proof. […]
Show full quote

A video proof.

Details in the last section of the original post explaining the upgrade from 180 to 200 MHz on air cooling.

A little bit ago I emulated the mods pioneered by pshipkov & others on this forum for the Lucky Star LS-486 Rev D. Was able to squeeze out another 0.1 fps by using a 32mb LGS simm that runs at "fastest". However, the board still has the same drawbacks as described before, such as needing a PCI 1/2 bus divider for stability.

I have found pretty much all of these SiS 496 boards to be unreliable with the PCI at 1/2.

Very cool @jonf.
Share a photo of the memory module.
32mb at "fastest" is rare, unique i would say.
I think this alone gave you the +0.1 fps.
Will update the charts for your achievement here.

@feipoa
At 3x66 1/2:1 is the only way to stability for LSD and similar boards.

pshipkov wrote on 2024-03-22, 22:43:

At 3x66 1/2:1 is the only way to stability for LSD and similar boards.

I can believe that. I didn't do much testing at 66 MHz because the floppy controller on LSD doesn't work at this FSB.

Otherwise, for PCI: 1/2 FSB, my notes indicate the following:

Could not use my Am5x86 QFP on interposer with PCI at 1/2. Must use ceramic PGA chip. Strange.

ISA sound would not function with PCI at 1/2. Tried several ISA sound cards. Tried two motherboards, same issue. Winamp hangs up immediately. pshipkov did not witness this issue. Since I have some DOS Quake scores with sound, I think the sound issue may have been limited to Windows 95. I don't recall.

Promise PCI IDE controller hangs up with PCI at 1/2. However, it will work if setting PCI Master Burst Read/Write to disabled. This reduces throughput by 70%. I think there was some other performance hit as well, but I forget.

Even onboard IDE not working well at 1/2 PCI. I don't recall the symptoms, and I don't recall.

I spent almost a year on this motherboard trying to get 180 MHz working well, but eventually gave up in favour of the M919.

pshipkov wrote on 2024-03-22, 22:43:

Very cool @jonf.
Share a photo of the memory module.
32mb at "fastest" is rare, unique i would say.

Here are a couple pictures, it is a pretty nondescript module

5x86 is really a 486 CPU? I doubt it.

385387386 wrote on 2024-04-29, 08:21:

5x86 is really a 486 CPU? I doubt it.

haha, is this bait? Am5x86, Cx5x86, and i486 only conform to the 486 instruction set.

feipoa wrote on 2024-04-29, 08:31:

385387386 wrote on 2024-04-29, 08:21:

5x86 is really a 486 CPU? I doubt it.

haha, is this bait? Am5x86, Cx5x86, and i486 only conform to the 486 instruction set.

Absolutely no offensive. I curiously read from Wiki, the 5x86 seems like a derivative from Cyrix M1.

The 5x86(Cyrix) seems more like a 6th generation architecture fit in a 486 package.

The Cyrix 5x86 incorporated some features from the Cyrix M1 (6x86), but they were disabled by default, either due to instability or to avoid product cannibalization. However, even the 6x86 was not fully compatible with the Intel Pentium and identified itself as a 486, despite being a socket 7 CPU.

There's an interesting series of videos on the Bits und Bolts YouTube channel where the host tries to play Tomb Raider with a Voodoo card. Here's the segment about Cyrix 5x86: https://www.youtube.com/watch?v=_Bj1dvtfzO0&t=624s

sysctl wrote on 2024-04-29, 09:56:

The Cyrix 5x86 incorporated some features from the Cyrix M1 (6x86), but they were disabled by default, either due to instability or to avoid product cannibalization. However, even the 6x86 was not fully compatible with the Intel Pentium and identified itself as a 486, despite being a socket 7 CPU.

There's an interesting series of videos on the Bits und Bolts YouTube channel where the host tries to play Tomb Raider with a Voodoo card. Here's the segment about Cyrix 5x86: https://www.youtube.com/watch?v=_Bj1dvtfzO0&t=624s

Awesome, the Cyrix 5x86 performed pretty well!

feipoa wrote on 2024-03-22, 21:26:

I have found pretty much all of these SiS 496 boards to be unreliable with the PCI at 1/2.

This is commensurate with my experience as well

Sorry to be a noob here, but I want to ask: does Cyrix/IBM 5x86 supports CPUID?

roytam1 wrote on 2024-05-22, 13:04:

Sorry to be a noob here, but I want to ask: does Cyrix/IBM 5x86 supports CPUID?

Yes, it does.

Just first 486's (mainly SX, DX and the first DX2's) did not support CPUID.
Some of the DX4 did not have CPUID support either (AMD 486 NV8T, V8T).
I'm not sure about SX2 and first Intel DX4 versions.

However, Cyrix' 486 do have MSRs (model specific registers) too.

Random question, should i change my dx4-100 with vlb at 33 to a dx2-80 and try at 40? Will it be significant? vga has 60n

pitchshifter wrote on 2024-11-11, 11:32:

Random question, should i change my dx4-100 with vlb at 33 to a dx2-80 and try at 40? Will it be significant? vga has 60n

That depends whether your board supports 3.3 Volt CPUs or not.
A DX2-80 basically needs 5 Volt, a DX4 needs 3.3 Volt. Please check this first.

You can jumper your DX4 from its 3x clock to a 2x clock.
Then you can keep your DX4 but running as DX2-80.

You also have to check whether your VLB cards are running at 40 MHz.
Please also check what kind of DX4 you use, and whether your L1 cache is operating in WB or WT mode.

Well i got a its st with 5v and an amd with 3v..
I should use the amd,
Regarding my dx4, its a intel write though.
Cache is write back.
If i change clock in my dx4 it Will work well at 40fsb?

With DX4 please check first whether you have jumpered it to x2 mode.
Perhaps one of the Intel DX4 users can tell whether it has a 2,5x mode, since I never had one.

When you have checked it is NOT running in x3 mode anymore but having 3.3 Volt, it is very likely it would run with 40 MHz too.
Don't try it vice versa!