VOGONS


First post, by Tyrhus

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This post is part a build showcase and a PC chips M918 appreciation thread.

IMG20240407180254-1.jpg

I've been tweaking this build for several months, going through several CPUs and graphic cards but here are the final (for now)) specs:

-PC chips M918 rev 1.2a with original 7/21/1995 bios
-512kb of L2 cache
-Am586 x5 p-75 ADW running at 3.3v/160mhz
-32mb of EDO ram
-Ark 1000pv stingray 1mb PCI
-Yamaha audician 32+Roland sc55

IMG20240407083945.jpg received-1713008536126590.jpg
received-1172929107613436.jpg

I know PC Chips gets a bad reputation for cheap construction and Fake cache chips, but I see no problem with this m918. It's stable and is compatible with most if not all 486 CPUs.
I also begin to think it's one of the fastest late 486 board!
Indeed my benchmark results are much higher than what I can see online.
All the timings are at their lowest and this thing never crashes!!!!
IMG20241013115500.jpg
IMG20241013113955.jpg

Using Phil's benchmark suit:
-Sysinfo: 346.5
IMG20241013115755.jpg
- Speedsys: 60.06 (245.28Mb/s memory bandwidth
L1 141.78/L2 59.78/M.T 54.78mb/s
IMG20241013120430.jpg

-Doom 60.3fps
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-Quake 18.3
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In 3d bench I get a score of 105.2 and in Pc player 27.3.

My findings doing this build:
-You can run the am586 X5 without using a later bios contrary to what is said on some documents online. Mine runs fine but strangely L1 cache isn't activated by default, i need to use setmul in autoexec.bat to do so.
-Running the am586 results in distorted sound FX in some rare instance (nuclear logo in Duke Nukem 3D but not in game)
-the two cyrix related bios option result in tiny performance improvements.

All in all, this build is a real keeper, it's stupidly fast for a 486 while being stable as a rock. Quake is definitely playable, Duke Nukem 3d in 320x400 is butter smooth and so is Terminal Velocity.
I will go on with my quest of the ultimate late 486 with trying to set up my Cyrix 586 100gp later on and I will keep tring to get my hand on a Pod 83 at a good price.
Compared to the infamous m919, the m918 is much more easy to set up (no serial bug, no weird Vlb/soundcard interaction, no stupid PCI divider etc etc...) too so I can't recommend it enough !

Reply 1 of 11, by pshipkov

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It may be difficult to invoke appreciation about this particular motherboard from others who played with it, but you certainly achieved very interesting results with it.
Its handling of L2 cache is on the same level of weird as the M919 issues you mentioned, but apparently you were able to work it out nicely.
Documented some of my struggles here with more details in the following replies in the same thread, for reference.
Nice hint about setmul for enabling the L2 cache. Didn't think of that. Will try it soon. Maybe that's the silver bullet.

Why 512Kb of L2 cache only ?
You can squeeze few more bits of perf with 1024Kb buffer.

Your Quake 1 score is very good.
Doom and PC Player are up there too.

Thanks for sharing.

(btw, this board has the chops for 200MHz (4x50), but not fully stable)

retro bits and bytes

Reply 2 of 11, by Many Bothans

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Very nice Tyrhus!

If you get a chance, can you try running nocash's MP3 encoder benchmark and report back? Mp3 decoder

Tiido and I got wildly different results on our higher end 486s.

  • Zenith Z386SX-20, 8MB FPM, Video 7 1024i, Unhoused
  • AOpen AP43, Am5x86-133@160, 1MB L2, 128MB FPM, Stealth III S540 32MB Savage4, SB32 w/ 8MB
  • Asus CUV4X-E, P3-933, 512MB PC133, Hercules 3D Prophet II MX 32MB, SB Live!

Reply 3 of 11, by Tyrhus

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pshipkov wrote on 2024-10-13, 17:28:
It may be difficult to invoke appreciation about this particular motherboard from others who played with it, but you certainly a […]
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It may be difficult to invoke appreciation about this particular motherboard from others who played with it, but you certainly achieved very interesting results with it.
Its handling of L2 cache is on the same level of weird as the M919 issues you mentioned, but apparently you were able to work it out nicely.
Documented some of my struggles here with more details in the following replies in the same thread, for reference.
Nice hint about setmul for enabling the L2 cache. Didn't think of that. Will try it soon. Maybe that's the silver bullet.

Why 512Kb of L2 cache only ?
You can squeeze few more bits of perf with 1024Kb buffer.

Your Quake 1 score is very good.
Doom and PC Player are up there too.

Thanks for sharing.

(btw, this board has the chops for 200MHz (4x50), but not fully stable)

The post you linked is a really interesting read with loads of infos.

Reading it I think I may have a solution for your struggle with L2 cache.

While tinkering with my board I tried all 4 different bios I could find online. And the later ones were crippling the performance or just plain bugged the thing.

The original 7/21/95 is the best and fastest.
One of the later ones available online (the 1/1/96 I think) gave me the same false L2 cache reading during boot, reporting only 256kb while the older bios worked fine.

I would suggest rolling back to this 7/21/95 bios if you never tried.
Some bios are made for the amptron version and it seems it's not suitable for the PC Chips varient

My board is a 1.2a and yours a 1.2 so maybe it won't work with yours who knows?

I can also agree that this MB is just acting weird sometimes:
I got it with a 120mhz AMD DX 4 that was in fact a 586 in disguise. It has 16kb of WB cache and can be run at 133mhz , being detected as a 586 X5, but refused to boot at 160mhz.
With this cpu I could run SRAM at 2-1-1-1 when using a single bank of 256kb and 3-1-1-1 when using 512kb.
With the am5x86 X5, I can run SRAM at 2-1-1-1 with the same 512kb dual bank.
Weird...

I always thought 512kb was enough, but now that you say it, I wanna try with 1mb of cache!

Reply 4 of 11, by Tyrhus

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Many Bothans wrote on 2024-10-13, 18:55:

Very nice Tyrhus!

If you get a chance, can you try running nocash's MP3 encoder benchmark and report back? Mp3 decoder

Tiido and I got wildly different results on our higher end 486s.

Thanks this machine was a real pleasure to assemble and tune and I'm pretty satisfied with the result!

Give me a few days to wrap my head around what HXdos is and how can I run this tool in my dos only PC and I will get back to you!

Reply 5 of 11, by Bruno128

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And does turbo function work with that amd?
To what performance levels can you turbo it?
Do you have “suspend / green break” vs “turbo” choice in that AMI WinBIOS?

SBEMU compatibility reports list | Navigation thread


Now playing:
Gold Rush: My VLB 486 (now with SC-55)
Baldur's Gate: Bridging compatibility gap in this year 2000 build
Arcanum: Acrylic 2003 build (January 2024)

Reply 6 of 11, by Tyrhus

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Bruno128 wrote on 2024-10-15, 17:39:

And does turbo function work with that amd?
To what performance levels can you turbo it?
Do you have “suspend / green break” vs “turbo” choice in that AMI WinBIOS?

The turbo function dimish the Norton sysinfo score by 0.5 points.
I don't know the exact reason but the WB CPU doesn't work with turbo function.
If I remember correctly, the Intel dw4 WT seems to work with turbo.
But you can always disable l1 cache.

There is a power saving menu in the bios but not sure about the suspens/green break option. I will check tomorrow.

Reply 7 of 11, by Intel486dx33

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I have an AMD 5x86 running at 160mhz too.
It Still can’t play MP3’s or Most Video’s.
So what is the point ?
You Need a Pentium class computer for this.

The 5x86 barely runs Win95.

Reply 8 of 11, by Bruno128

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I prefer thinking that this shitposter is a bot rather than insane person

SBEMU compatibility reports list | Navigation thread


Now playing:
Gold Rush: My VLB 486 (now with SC-55)
Baldur's Gate: Bridging compatibility gap in this year 2000 build
Arcanum: Acrylic 2003 build (January 2024)

Reply 9 of 11, by theelf

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Intel486dx33 wrote on 2024-10-20, 16:18:
I have an AMD 5x86 running at 160mhz too. It Still can’t play MP3’s or Most Video’s. So what is the point ? You Need a Pentium c […]
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I have an AMD 5x86 running at 160mhz too.
It Still can’t play MP3’s or Most Video’s.
So what is the point ?
You Need a Pentium class computer for this.

The 5x86 barely runs Win95.

I have a cyrix 5x86 running at 120mhz, before i have a amd 5x86 at 160mhz, and never have any problem to play mp3 files, even at 320kbp. In win31 i can play 64kb stereo mp3 in background while doing some work without problem, for example excel work or programming in visual basic 3

Win95 or NT4 works fine, i use NT4 for basiegaxorz programming in 486 and is fine too

Reply 10 of 11, by Bruno128

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Tyrhus wrote on 2024-10-18, 21:27:

There is a power saving menu in the bios but not sure about the suspens/green break option. I will check tomorrow.

I meant the one like pictured here:
Re: Turbo button on 486 acts like a 'sleep' button

SBEMU compatibility reports list | Navigation thread


Now playing:
Gold Rush: My VLB 486 (now with SC-55)
Baldur's Gate: Bridging compatibility gap in this year 2000 build
Arcanum: Acrylic 2003 build (January 2024)

Reply 11 of 11, by Tyrhus

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Bruno128 wrote on 2024-10-24, 19:28:
Tyrhus wrote on 2024-10-18, 21:27:

There is a power saving menu in the bios but not sure about the suspens/green break option. I will check tomorrow.

I meant the one like pictured here:
Re: Turbo button on 486 acts like a 'sleep' button

Oh I will look for that tonight! I never explored the menu. What would be the use of that ?

Some updates with my build.
I tried to make my Cyrix 5X86 Work with its hidden parameters but the scores are really low. I need to try again but the scores were really disappointing... The AMD is far simpler and is a real power house at 160mhz!

I also finally got my hand on POD 83mhz!
This cpu is really cool and i have great scores with it and it's really close to my socket 5 + p100 experiment.
Unfortunately i didn't have enough luck to score a CPU that can run at 100mhz out of the box. At 100mhz this setup would be really close to a "real" pentium setup.

I'm getting Divide Overflow errors left and right when overclocked . Does someone know what does it means ?

Here are my results with the pod at stock speed:

Speedsys 61.56 (204.40) 163.15/49.07/43.08
Doom 51.2
Quake 22.6
3d Bench 86.3
Pc Player 23.8
Sys info 264.7

I'm really tempted to do the diode mode to run it at 100mhz, but I don't want to ruin such a collector pièce!