Mvickers03 wrote on 2020-12-14, 09:49:

No I’m not joking mate. I’m actually looking for a board that can run the PCI bus at 33 and CPU at 66 so it’s stable. From what I’ve read even at 40 the PCI bus is unstable.

If you want to teach me something go ahead. Or even better sell me a board suitable for overclocking 😉

These threads should help with your education about PCI dividers on SIS 496 chipset based boards .

SiS 486 Chipset Datasheets
Any SiS-based 486 motherboards with 2/3 or 1/2 PCI multiplier?

EDIT: 66MHz CPU base clock might still be pushing it.

It is definitely possible to find a motherboard and expansion card set that is stable at with a 40 MHz FSB. Find that is probably easier to finding a 486 set that works well with a 66 Mhz FSB.

feipoa wrote on 2020-12-14, 11:28:

It is definitely possible to find a motherboard and expansion card set that is stable at with a 40 MHz FSB. Find that is probably easier to finding a 486 set that works well with a 66 Mhz FSB.

I had such a setup in the mid nineties :

- A SIS 496 based board
- AMD 586 133MHz CPU running at 160 MHz (4x40MHz)
- S3 Trio64V+ based video card
- 16MB FPM 72-pin RAM SIMM
- Realtek RTL8029 based PCI NIC
- a couple of ISA sound cards

It ran fine except for the DIMM going bad eventually which motivated the switch to a 150MHz Pentium in late 1997 . AFAICR, that 486 system kept on chugging for years at a friend's place after the RAM was replaced .

EDIT: AFAICR, I was able to get that system to POST and boot to DOS at 180MHz (3x60MHz) using undocumented jumper settings, but that was hopelessly unstable. I cannot recall what I did with PCI clock divider settings .

darry wrote on 2020-12-14, 10:23:

These threads should help with your education about PCI dividers on SIS 496 chipset based boards . […]
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Mvickers03 wrote on 2020-12-14, 09:49:

No I’m not joking mate. I’m actually looking for a board that can run the PCI bus at 33 and CPU at 66 so it’s stable. From what I’ve read even at 40 the PCI bus is unstable.

If you want to teach me something go ahead. Or even better sell me a board suitable for overclocking 😉

These threads should help with your education about PCI dividers on SIS 496 chipset based boards .

SiS 486 Chipset Datasheets
Any SiS-based 486 motherboards with 2/3 or 1/2 PCI multiplier?

EDIT: 66MHz CPU base clock might still be pushing it.

Thank you, I have read these already.

This is exactly what I was talking about. I need a motherboard with divider for FSB otherwise it just wont be good for overclocking.

Any old PCI 486 mobo with PCI will not cut it.

feipoa wrote on 2020-12-14, 11:28:

It is definitely possible to find a motherboard and expansion card set that is stable at with a 40 MHz FSB. Find that is probably easier to finding a 486 set that works well with a 66 Mhz FSB.

I'll be patient mate. Are you still running the MTI486