I suggest to try Restart in md-dos mode after boot on windows and check if there is a performance difference.
I remember there was a topic about similar issue with via chipset for slot1\socket 370

Nemo1985 wrote on 2023-02-13, 21:05:

I suggest to try Restart in md-dos mode after boot on windows and check if there is a performance difference.
I remember there was a topic about similar issue with via chipset for slot1\socket 370

Tried that too. Always use a pif and restart in dos mode. Tried playing with the autoexec and config and even tried from a 6.22 bootdisk.
Will do a search for the via post to see if there are any other things to try.

corgi74 wrote on 2023-02-13, 19:44:

I recently picked up a Jetway 920BF motherboard with a SIS620 chipset that has a slot 1 and socket 370. I’ve tried a slot 1 P2 350, 233 and Celeron 233 as well a PIII 600E in it and all give strange results in DOS using Phil’s benchmarks.
In 3DBench 1.0c I get 75 with theCeleron, 85.4 with the PII 233, 95 with the 350 and 110.7 with the PIII 600E. All are well below what I would expect as my K6-2 400 in my socket 7 system is over 200.

Are you getting strange results in many/all Phil’s benchmarks or just 3DBench?

I think it may be related to the poor performance of the memory subsystem. PCChips M747 / SiS 600 Tuning: The Anti Thesis Thread. NOT the bane of MY existence..
Aside from that, have you tried MTTRLFBE or FASTVID ? https://www.philscomputerlab.com/dos-graphics-boost.html

konc wrote on 2023-02-14, 09:57:

corgi74 wrote on 2023-02-13, 19:44:

I recently picked up a Jetway 920BF motherboard with a SIS620 chipset that has a slot 1 and socket 370. I’ve tried a slot 1 P2 350, 233 and Celeron 233 as well a PIII 600E in it and all give strange results in DOS using Phil’s benchmarks.
In 3DBench 1.0c I get 75 with theCeleron, 85.4 with the PII 233, 95 with the 350 and 110.7 with the PIII 600E. All are well below what I would expect as my K6-2 400 in my socket 7 system is over 200.

Are you getting strange results in many/all Phil’s benchmarks or just 3DBench?

All of them unfortunately. Got 1734 ticks in Doom.

zyga64 wrote on 2023-02-14, 10:04:

I think it may be related to the poor performance of the memory subsystem. PCChips M747 / SiS 600 Tuning: The Anti Thesis Thread. NOT the bane of MY existence..
Aside from that, have you tried MTTRLFBE or FASTVID ? https://www.philscomputerlab.com/dos-graphics-boost.html

Thanks for this link. Some of this makes sense. The onboard audio is always enabled in windows even if the jumper is set to disable it and it’s the same for the serial and parallel ports.

You may play with PCI registers also in plain DOS: TweakPCI - A DOS utility to view/modify PCI configuration registers
The question is: how close is the SIS620 to the SIS600 ? (there is a pretty good chance that they are very similar).