My bad the 142 IS 940 the rest are 939.
It's been years so pardon my memory.... if it's flaky...
IIRC The P3 multiplier is locked and the only way to overclock is by cranking up the FSB.
The 440BX normally can only handle 100MHz FSB so that might be hard.
If your motherboard allows you to, you might be able to tweak the FSB a little.
Since it is a Dell motherboard I doubt it has OC capabilities.
If you had an Abit or other OC friendly motherboard then maybe....
I used to OC Celerons from 66MHz FSB to 100MHz FSB on Abit BH-6 Slot1 motherboards with i440BX chipsets.
"I think" you have to solder the Slot1 to bypass the clock multiplier lock if you can't change the FSB frequency.
Good Luck
PS You might be able to get a significantly faster Slot1 CPU online maybe @ compgeeks.com, ebay or elsewhere if your board supports more than 600MHz. I believe with a BIOS upgrade the 440BX can probably handle up to a 1GHz P3 Coppermine with 100MHz FSB if you can find one that is.