1. That Celeron is based on a Tualatin core . That KIT370 converter probably does not support Tualatin core CPUs . Relatively few Socket 370 to Slot 1 converters support such CPUs with without modifications (to the CPU or converter) . Upgradeware and PowerLeap are the only two manufacturers I know of that did, in at least some of their models .
2. That 500 MHz may well not be very overclockable .

EDIT: Corrected typo

Agree darry ! The BX-6 r2 had very little success in overall cpu support above 600Mhz and very little OC from what little I know compared to other late model 440BX boards, it was about same par as Asus P2B, not P3B . Not saying you cannot get a 1.2 ghz SL5XS Celeron with proper Slocket to work but I know of no 500mhz/66Mhz Celeron to work at 100Mhz bus on a BX but you may be able to get 75 or 83Mhz clock to work on that 500Mhz celeron)
Last BIOS readme:
Model: BX6 2.0
Bios Issue Date: 2000/05/08
BIOS ID: QR
1. Fixes the incorrect memory capacity issue under Linux.
2. Fixes the ACPI issue under W2K.
3. Improves the Power On function by mouse right/left botton after shutting down the system under Win98SE.
4. Supports Celeron 566(66) and 600(66) MHz CPUs.

Thanks darry and Horun for the advice. I have good electronics skills, is there a link to said modification? (I have done some forum searching but maybe I'm missing it.)

I went ahead and tried the 75 Mhz with 7.0X at ~563 Mhz and that seems to be working fine. Any multipliers over 7 seem to be useless (same 563 Mhz). If I try the 83 Mhz range, I see a ~634 Mhz but Windows 98 will hang on loading. Any modifications will give the unsupported CPU BIOS error that I must F1 through.

I'll start looking out for those brands of cards in the meantime. I'm really trying to squeeze Morrowind out of my old system. 😀

May be more an issue with the basic Slot 1 adapter than the board (is this the one?)

Found one post online of someone OC'ing a coppermine Celeron 600MHz (9 x 66) to 900MHz (9 x 100) on a BX6r2 tho they didn't say which bios / adapter combo they were using.

Tom's Hardware published a comprehensive guide to Celeron overclocking in 2000.
https://www.tomshardware.com/reviews/intel-ce … -guide,218.html
Page 6 has a lot of details:
https://www.tomshardware.com/reviews/intel-ce … uide,218-6.html

A rule of fist for later Coppermine Celerons is that the CD steppings seem to give the best shot at success.

I used to run a Celeron 633 @ 950 on the BX6 v2.0 back in the day, through Abit's SlotKet III adapter, and didn't experience any particular stability issues with it. It can definitely handle 100 MHz FSB Celerons just fine.

The reason a 500 MHz Celeron won't run at 100 MHz FSB has nothing to do with the board and everything to do with the CPU itself. It would have to run at 750 MHz, which you're going to need some extreme overvolting to ever hope to achieve, and even then there's no guarantee. Mendocino based Celerons usually max out around 550-600 MHz at normal voltages. Best Celerons to overclock are 300-400 MHz models, most of those should run at 100 MHz FSB (a 50% overclock) with at worst a couple 0.1 extra Volts. With the 500 MHz chip, you're most likely limited to 7.5 x 75 MHz, maybe 7.5 x 83 MHz if you're lucky and willing to feed it some extra voltage.

nwsw wrote on 2020-06-29, 04:09:

Thanks darry and Horun for the advice. I have good electronics skills, is there a link to said modification? (I have done some forum searching but maybe I'm missing it.)

I went ahead and tried the 75 Mhz with 7.0X at ~563 Mhz and that seems to be working fine. Any multipliers over 7 seem to be useless (same 563 Mhz). If I try the 83 Mhz range, I see a ~634 Mhz but Windows 98 will hang on loading. Any modifications will give the unsupported CPU BIOS error that I must F1 through.

I'll start looking out for those brands of cards in the meantime. I'm really trying to squeeze Morrowind out of my old system. 😀

You will likely need a patched BIOS for the F1 issue (not sure if adding microcode for the CPU in question will suffice).

Very important note: Tualatin cores run on lower voltages than previous socket 370 CPUs. The socket to slot adapter must be able to present proper VID for the board to know what voltage to send AND the board's VRM must be able to supply that requested voltage . The only exception I know of is the PowerLeap adapter (ip3/t), which has an integrated VRM . Unfortunately, it is hard to find and usually expensive .

As for the modifications required, here is an example for an MS-6905.
https://www.oocities.org/_lunchbox/ms6905_tualatin_mod.html

Don't forget that cpu is multiplier locked, so no matter what you set, it will still run at 7.5 multiplier. No way to get around that, unfortunately ..

PC Hoarder Patrol wrote on 2020-06-29, 05:13:

May be more an issue with the basic Slot 1 adapter than the board (is this the one?)

KIT370 Slot 1 Adapter.jpg

Found one post online of someone OC'ing a coppermine Celeron 600MHz (9 x 66) to 900MHz (9 x 100) on a BX6r2 tho they didn't say which bios / adapter combo they were using.

That is correct, the heatsink also looks identical.