VOGONS


First post, by retro games 100

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(Solved: post #4) Yet another ebay transaction goes wrong. I bought a fairly expensive Intel DX4-100 SK096 model, and I double-checked with the seller that the code was correct: SK096. That's the write back cache model. The ebay seller confirms this - "yes that's the one you'll receive". So, I open the package this morning, and I get the common non writeback cache SK051 version. Rather than toss it in the recycle bin, I see if it works. The weird thing is, it won't run at its default speed. If I run chkcpu.exe, it says:

Internal CPU speed: 67.2 MHz
Clock Multiplier: 3.0
Bus clock speed: 22.4 MHz

What's up with the low bus clock speed? The bus jumpers are set to 33 MHz. Unless my overclocking experiments have fried the bus clock jumper speed circuitry on this mobo? I've double-checked this 486 Biostar MB-8433UUD-A mobo's jumper settings on this webpage, and I'm sure I've got them right. Any ideas please people? Thanks a lot for any advice.

Last edited by retro games 100 on 2011-02-18, 17:38. Edited 2 times in total.

Reply 2 of 5, by retro games 100

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Yes of course.

1) Immediately to the left of PCI slot #3, you can see the 3 bus speed jumpers. They are all covered. That means 33 MHz bus speed.

2) Immediately to the north of the heatsink, and to the left of the EDO stick, you can see 3 voltage jumpers. That means 3.45 volts.

3) One inch to the left of the heatsink's left edge, you can see the CPU selection jumpers. I think this means DX4.

4) The other jumpers are immediately north of the cache chips. They control the cache settings, and the CPU selection setting. I have never touched these, because their "1&2 1&2" setting applies to all of the CPUs I have ever tested.

I am beginning to worry about this mobo. I have tested another DX4 chip. This time it's a SK096 write back model. That chip also runs at 66 MHz with an unusual slower bus speed. I then tested a 3rd chip, this time a writeback DX2-66 chip. The machine behaves oddly, and locks up after booting DOS, or locks up when I run chkcpu.exe. I put the AMD 5x86 P75 back in to the mobo, and that runs OK - phew!

PICT2078.JPG

66.jpg

Reply 3 of 5, by Old Thrashbarg

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Looks like you may have JP45 and JP46 mixed up compared to the jumper diagram you linked. According to that, the blue jumper should be on pins 4&5 of JP46, not JP45.

Reply 4 of 5, by retro games 100

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Old Thrashbarg, and 5u3, and all of the other retro oracles on Vogons: It's a good job you guys are here, to help out morons like me, because that's exactly what I've done wrong. What can I say? How about Thank you very much! 😁