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PC Chips M912 ver:1.4 - dead board?

H

Half-Saint

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Apr 21, 2004
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322
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Ljubljana, Slovenia
I'm having trouble getting the board to boot.

The CPU is a Cyrix 486DX-40 w/ heatsink but no fans. When I turn it on, nothing happens: no beeps and no video but the PWR LED is on.

I tried two different video cards, one 16-bit ISA and one VLB. I'm using 72-pin SIMMs because that's all I've got. Tried booting the board with no RAM but still don't get any beeps.

I configured the jumpers according to the manual found here:
http://motherboards.mbarron.net/models/486vlb3/m912v14.htm

Anything else I can try?
 
Make sure your 72-pin is FPM and not EDO. Try inserting it in the other simm slot.
 
Is there a jumper to write protect the Flash BIOS chip? If not (or write protection was disabled when you got the board), it's possible that it's a victim of the CIH virus.
 
You must have 30 pin simms! 4 the same size. Either 256k, 1 MB or 4 MB density. Look at the link you provided. The black and white pictures specifically call the 30 pin simms as bank 0. Bank 0 must be full before the other banks will work. So just using 72 pin simms won't do it. Hope this helps. If you need some 30 pins ask around. I know I have some id interested. Or if your lucky you might find some locally.
 
Chromedome45 said:
You must have 30 pin simms! 4 the same size. Either 256k, 1 MB or 4 MB density. Look at the link you provided. The black and white pictures specifically call the 30 pin simms as bank 0. Bank 0 must be full before the other banks will work. So just using 72 pin simms won't do it. Hope this helps. If you need some 30 pins ask around. I know I have some id interested. Or if your lucky you might find some locally.
Click to expand...
Not so. This, from the manual:

There are 2 banks of 72 pins SIMM socket and 1 bank of 30 pins SIMM socket on this board, each bank of 72 pins SIMM consists of only one SIMM socket as denoted as Bank 1, Bank 2; Bank 0 is the socket for the 30 pins' SIMMs. These three banks are not required to be filled in sequence as in Bank 0 first and Bank 3 last. The system board has auto-detection circuitry to sense which bank or banks are filled.


So Bank 0 is not required in order to make use of the other banks.
 
Half-Saint said:
I'm having trouble getting the board to boot.

The CPU is a Cyrix 486DX-40 w/ heatsink but no fans. When I turn it on, nothing happens: no beeps and no video but the PWR LED is on.

I tried two different video cards, one 16-bit ISA and one VLB. I'm using 72-pin SIMMs because that's all I've got. Tried booting the board with no RAM but still don't get any beeps.

I configured the jumpers according to the manual found here:
http://motherboards.mbarron.net/models/486vlb3/m912v14.htm

Anything else I can try?
Click to expand...

It could be a broken CPU, you could try a different 486 chip.
 
A broken PCchips board you say? It sounds like it's operating normally.

I've never used a Cyrix 486 chip before. Aren't those things jumpered differently than intel CPUs? I noticed many of them require 4V, which not every 486 board supports.
 
Half-Saint said:
All of my 72-pin RAM is declared -60 which I presume is EDO.

Surprisingly the board doesn't beep even with no memory installed.
Click to expand...

EDO will not work with this board for sure. But being 60 ns does not mean that it will also be EDO.

Anonymous Coward said:
A broken PCchips board you say? It sounds like it's operating normally.

I've never used a Cyrix 486 chip before. Aren't those things jumpered differently than intel CPUs? I noticed many of them require 4V, which not every 486 board supports.
Click to expand...

I expect this to be a 5V CPU, so there shouldn't be any such kind of problem, assuming the board is not locked at 3.3V. If it is a 4V one, that is unlikely for a 40 MHz CPU and the board only has 3.3V and 5V options, you can try setting the FSB at 33 MHz, with 3.3V and it should work, not full speed, but it would at least prevent any CPU-related POST problems. Oh and BTW, you can also give a try with jumpering it as an Intel DX-33 if nothing works. I've had a board (386) that although it had specific jumper settings for the Cyrix 486DLC-40, it wouldn't post with those and only would if jumpered as a regular 386-40
 
The board has the option for 3.3V, 4V or 5V. I jumpered it for cyrix DX40. Also tried Intel settings but it didn't do anything. Will try a proper intel 486 when I have the time.
 
The Cyrix 486DX and DX2 chips were 5 volts, like Intel. I used a few of them to give cheap upgrade to SX systems way, way back when. They weren't quite as fast as an Intel or AMD chip for some reason, but they were faster than the DLC chips.

Do be aware that PC Chips motherboards were very cheaply made and unreliable, even when they actually put chips on the board that worked.
 
Dave Farquhar said:
The Cyrix 486DX and DX2 chips were 5 volts, like Intel. I used a few of them to give cheap upgrade to SX systems way, way back when. They weren't quite as fast as an Intel or AMD chip for some reason, but they were faster than the DLC chips.

Do be aware that PC Chips motherboards were very cheaply made and unreliable, even when they actually put chips on the board that worked.
Click to expand...

Are you certain? I've seen documents on the internets that claim 4V for these chips. Maybe there are multiple versions.
 
Sorry for resurrecting this old thread, but did you try booting it up with an ISA controller card installed ? I remember when I had this mobo it wouldn't boot nor beep nor anything without a controller card installed.
 
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