Dell Dimension XPS B Processor Upgrade Information
compiled by Robert Hancock
These systems use a Dell OEM version of the the Intel VC820 motherboard. However, the Bxxx (not Bxxxr) machines use an FC-PGA processor instead of a Slot 1, which does not appear to be an option on the standard VC820. (At least, that's what Dell's support site says. However, some people say that their Bxxxr machines have an FC-PGA processor on them. To be safe, pop the lid off your machine and see which you have before you buy a new CPU..)
For some dumb reason, Intel's support site says that these machines take 168-pin RDRAM modules. There is no such thing, all RDRAM RIMM modules are 184 pins.
For reference, the list of changes in all Dell BIOS versions for this system is available here. If you have a BIOS version earlier than A08 and want to upgrade the processor, I recommend you upgrade to the latest BIOS version, currently A08.
You should be able to use any Slot 1 (SECC2) Pentium III processor in the Bxxxr systems (either 100 or 133 MHz bus), or any FC-PGA chip using a slocket adapter. I have a report that the Asus S370-133 slocket doesn't work in these machines, but others like the Iwill Slocket II probably will. Celeron CPUs will not work (at least non-overclocked) as the motherboard does not support 66 MHz bus.
These systems should also be able to use the Powerleap PL-iP3/T CPU adapter, which allows the use of Tualatin-core Celeron CPUs at 1.2 GHz and up. Tualatin-core Pentium IIIs should theoretically work with this adapter as well - however I have heard some reports of problems with 133 MHz bus CPUs on these adapters. See the review of this adapter linked to on the main page for more information.
For the Bxxx machines using a socketed CPU, you should be able to use any FC-PGA Pentium III in these systems.
These boards use an ICS9250-09 PLL chip, which supports FSB speeds of 100 and 133 MHz only and is not software programmable. The only way to overclock a CPU on these machines would be to use a slocket and FC-PGA processor, and use the slocket's FSB select jumpers to run a Celeron processor at 100 MHz or a Pentium III chip with a normal 100 MHz FSB at 133 MHz. The latter overclocking method may not be feasible for some processors.
Note that these systems use RDRAM memory. SDRAM memory cannot be used. See the memory notes page for more details.