VOGONS


First post, by tikoellner

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Hi there!

I am trying to make my ASUS VL/I-486SV2GX4 rev. 2.0. work with IBM 5x86c CPU. Everything seems fine, but I don't actually know how to proceed with CPU voltage selection.

In the manuals which I found it's said that in order to set 3.3 volts I should use both JP32 and JP33. On the illustrations these jumpers are next to each other. My problem is that I could not locate JP33 at all. I only have JP32 with 3 pins in total.

I know that this may be related to my board being rev. 2.0., but I still have no clue which J32 settings is for what voltage.

I'll appreciate your help.

[EDIT:] OK, I found out that JP32 is only to fine-tune the voltage between 3.3 and 3.45 - as the board supports voltage autodetection (thus rendering JP33 obsolete). But is that true?

Reply 1 of 7, by feipoa

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I have the same motherboard revision.

If JP16 is shorted on 1-2, then JP32 sets the voltage. In which case,
JP32 1-2 = 3.45 V
JP32 2-3 = 3.6 V
JP32 OPEN = 4.0 V

If JP16 is OPEN, then the voltage is 5.0 V

Plan your life wisely, you'll be dead before you know it.

Reply 2 of 7, by tikoellner

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Thank you!

So it seems that 2.0. still has full variety of voltage options out of the box. I thought these were much more limited in 2.0. than in 2.1.

Oh wait, it has no 3.3v which I need for IBM 5x86 😀 Do you think running it at 3.45 will be OK?

Again, thanks.

Last edited by tikoellner on 2020-07-08, 19:57. Edited 1 time in total.

Reply 3 of 7, by feipoa

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Also, it is important that you update the BIOS to sv2g4021.bin for use with Am5x86 and Cx5x86 cpus. This means you will need to purchase a flashable EEPROM. I do not think any of these boards came with EEPROMs, that is, they all came with UV EPROMs, if I am not mistaken?

I also recall having issues using with a Cyrix 5x86 AND a VLB SCSI controller, however Am5x86 was fine. I think there was also an issue using a POD in WB mode if using a VLB SCSI controller. Am5x86 was fine in WB mode with VLB SCSI though.

IBM 5x86 prefers 3.45 V. Some Cyrix 5x86 chips won't even run at 3.3 V.

Plan your life wisely, you'll be dead before you know it.

Reply 4 of 7, by tikoellner

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Well, my at least is UV erasable. So I will not even be able to start without flashing BIOS? If so, I will get it flashed tomorrow.

BTW - do you maybe know if there are any other jumpers (apart from those mentioned in the manual) that I should look at to get it running properly with my CPU?

Reply 5 of 7, by feipoa

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I don't recal exactly what symptoms you will see if you don't upgrade the BIOS, but it is well known that you must upgrade the BIOS for 5x86 chips. While I was waiting for my EEPROM chips to arrive in the mail, I tried everything to get the Am5x86 working, but it was without hope. I want to say that the Am5x86 is recognised as a DX4-100 with WT cache and doesn't work properly.

Any other jumpers, well, I have noted that L2 in the BIOS must be set to Auto, not WB, for the memory speed to be correct. The motherboard has a working PS/2 mouse header! And there is some inconsistency as to what the proper CPU jumper settings are. Generally, I follow the scanned manual found on Vogons. I think Artex scanned it. Ihave noted that the Am5x86-160 needs 3.60 V, not 3.45 V. You may need to play around with the Synchronize, Transparent and Delay options in the BIOS depending on your graphics card. On my board, I had to set VESA clock delay (JP26) to "delay". Latch Local Bus set to T3, DRAM CAS Write to 2T. The Synchronize setting is slower, but is needed for some graphics cards. Transparent is faster.

I beleive JP20 is the clock multiplier. With JP20 1-2 is for 2/4x CPUs and JP20 Open is for 3x.

Good luck!

Plan your life wisely, you'll be dead before you know it.

Reply 6 of 7, by tikoellner

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Thank you for this valuable (as usual) advice. I think I will attempt to test the whole computer on a regular Intel DX2 and then mess with BIOS update, etc.

Reply 7 of 7, by feipoa

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I think that is what I did too.

Plan your life wisely, you'll be dead before you know it.