I searched and noticed that apparently Ipox is a brand related to Epox. They don't have many boards under the Ipox name, but I did see this one that matches your description:
http://www.ipoxusa.com/images/prodimgs/3eti23-b.jpg
http://www.ipoxusa.com/main/item.asp?itemid=52
Is that the board you have?
I'm pretty sure the Intel SE440BX-2 board will not support 133FSB. The 440BX chipset doesn't officially support that, and Intel doesn't support overclocking on their boards. They don't underclock either - they autodetect the CPUs intended bus speed, just like Intel wanted other motherboard manufacturers to do. I don't think that board will even let you boot with a 133FSB CPU - the BIOS will just tell you to march yourself back to the store and exchange it. Intel boards take themselves very seriously. They're great for supreme reliability, but not so great for screwing around with.
I don't know what options these boards' BIOSes have for disabling caches, but if you can, then disabling L1/L2 will slow down the CPU dramatically. I think you're more likely to see that option on an Epox/Ipox board than the Intel.
I don't know about Ipox, but
Epox boards of that period usually have the frontside bus speed controlled by a single jumper. That IPOX board photo that I linked above looks like it has the same kind of jumper block. You should be able to select down to 66MHz FSB, and maybe lower, to slow down the CPU at least that much. They will also let you try to run at higher bus speeds - I think the Epox boards I've seen go as high as 150MHz. How fast it can actually run stable is another question.
Epox used cheap capacitors on their boards. Intel used good parts on their boards. That Intel board is meant to be simple plug and play and reliable. Epox boards are budget enthusiast boards with more manual tweaking options.
Ipox might be better quality than Epox - it looks like they are/were marketed for industrial use. They might not be as tweakable, but probably still more tweakable than the Intel.
