Yes, the multiplier on that chip is locked. intel started doing this on the PII 266/Celeron 300 to prevent people from re-labling the chips and then reselling them.
Funny, now intel is doing just that, with the Celeron II 533a...calling it a 800E now.
No matter what you set the multi in the BIOS at , it will run what the chip's specific multi is.
Mr B