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View Full Version : a problem with replacing a motherboard



lambs4
12-20-2001, 04:17 PM
I'm trying to replace a 486 motherboard with a Pentium 133. The P133 is from another computer that I've recently upgraded, also. Therefore I'm sure it works.

My problem is that after installing the Pentium motherboard in the old computer and then when trying to boot it doesn't, instead it shows the famous blank screen. The strange thing to me is that when I put back in the older one then it is able to boot. Anyone have a suggestion of what my problem might be? I was thinking it could be the graphic card, but wouldn't figure it to be the problem.

Thanks for any help.

taylorguitarman
12-20-2001, 04:30 PM
What's the rest of the system?

lambs4
12-20-2001, 05:14 PM
I'm uncertain by what you mean by "the rest of the system". So I'm gonna take a guess.

The 486 motherboard contains:
A 486SX2 processor running at 80MHz
16MB - don't know what type

The 486 system itself contains:
'93 Trident graphics card
639MB HD running DOS/Win 3.1

The Pentium motherboard thats going to replace the above contains:
A Pentium 1 processor running at 133MHz
81MB SDRAM SIMM
'94 Trident graphics card

I don't know if this would be help, but maybe its the type of motherboard: P5I430VX250 Explorer

I hope the above leads to a solution to my problem.

novacain
12-20-2001, 10:57 PM
Any beep at POST?

Any other sounds (like the RAM counter)?

Remove all the components except the graphics card , processor and ONE mem stick. See if it will POST then. If it does add components.

Check the power supply is compatible. Some of the 486 had different power needs but I thought that was only the 486DX 4 100.

Remove the battery on the motherboard for a few minutes to reset it to the fail safe BIOS settings.

lambs4
12-21-2001, 04:00 PM
I thought that was only the 486DX 4 100.

My typo. It is a 486DX. I'll take your suggestions and try them within a months time or so.

The V.
12-21-2001, 09:20 PM
Originally posted by novacain
Any beep at POST?

Any other sounds (like the RAM counter)?

Remove all the components except the graphics card , processor and ONE mem stick. See if it will POST then. If it does add components.

Check the power supply is compatible. Some of the 486 had different power needs but I thought that was only the 486DX 4 100.

Remove the battery on the motherboard for a few minutes to reset it to the fail safe BIOS settings.

One mem stick may not cut it, most older motherboards have bank sizes that are either 2 or 4 SIMMS -- so unless he has a full bank, all filled with the same size modules, he won't get anything.

I take it both cases are AT form factor? Make sure you're not shorting any part of the motherboard to any metal part of the case.

novacain
01-02-2002, 11:40 PM
Yes, I forgot.

486 is probably 4 if it is not faster than 33.

sean
01-03-2002, 11:14 AM
Check the processor. If they're different, the machine code (which is what all the programs will get reduced to) could be referring to registers that don't exist. It's sounds like an older processor and won't have systems that the Pentium it's been set to has.