Intel i486 SX33
The SX33 was quite a good processor for a while. Both AMD and Cyrix made 33MHz parts as well but DX/2, DX/4 and even DX/5 parts from these companies can be found more easily. This is because AMD and Cyrix had to make their own 486 because Intel didn't gave the 'howto make a 486-manual' to AMD and Cyrix anymore. Both companies used the 386 as a foundation for their 486 processors and thus shipped their 486 on the market two years later. At that time the DX and DX/2 processors were becoming more popular.
Intel's SX33 processor was quite popular at the time. It is noticeably faster than the SX 25MHz.

