Dell Dimension XPS D Processor Upgrade Information
compiled by Robert Hancock
For reference, the list of changes in all Dell BIOS versions for this system is available here
These systems use a Dell OEM version of the Intel AL440LX motherboard.
Bill Selk has quite an extensive page dealing with the AL440LX board, it also has some info specific to the Dell version. Anyone planning to upgrade an XPS D system should probably consult his page.
This board supports 66 MHz FSB only, so Pentium III CPUs can't be used as they run at 100 or 133 MHz FSB - only Celeron CPUs can be used to upgrade. However, apparently SoftFSB can be used to increase the FSB speed over 66 MHz somewhat to overclock the Celeron (though not to 100 MHz, a realistic max of 72 - although one person reported being able to get their machine up to 80). This page on Bill Selk's site talks about overclocking with SoftFSB.
In order to upgrade to a Celeron, you need to install the Intel BIOS on the motherboard. This page on Bill Selk's site explains how to do this. You have to use the BIOS recovery method (or else hack the BIOS ID string with a hex editor) in order to flash it on, the standard Intel BIOS flashing method included with the Intel BIOS file won't work on a Dell board. A list of changes for all Intel BIOS revisions for this motherboard is available here.
Celerons up to 533 MHz (not the A version of the 533) can be used with little problem. However, this board apparently supports a minimum core voltage output of 1.8 volts, compared to the 1.5 to 1.7 volts that the newer Celerons (533A and faster) require. If you use a slocket with the auto voltage setting or set the voltage manually to below 1.8 volts, it seems it doesn't provide any power at all and won't boot up. If you set the voltage to 1.8 volts, it'll boot, but you are somewhat overstressing the processor. It should be OK if adequate cooling is provided, but it may shorten the processor life. However, a number of people are running Celerons at 1.80 volts with no apparent problems. To use the proper voltage for the Celeron-533A and up, you'd have to use a slocket that has an onboard regulator to overcome the motherboard limitations, like the PowerLeap PL-iP3.
One problem with the newer Celeron FC-PGA processors (533A MHz and up) and these systems seems to be with non-3dfx AGP video cards. It seems that sometimes people experience lockups while playing 3D games. This problem does not seem to occur with 3dfx video cards - probably because they don't use as many AGP features as other cards. PowerLeap has this to say on the subject:
Important note: we've found that the Intel 440LX chipset supports AGP 1.0, and when upgraded to the Celeron-II will not work with certain AGP 2.0 VGA cards in 3D accelerated mode, even if they worked before the CPU is upgraded. This would include any GeForce-based cards, ATI Radeon, and many nVidia TNT/ TNT2 cards. One very notable exception to this are the 3DFX VooDoo cards, including the latest VooDoo 5 5500, which works very well with the 440LX chipset even when the CPU has been upgraded to a Celeron-II 500 MHz CPU (using the PL-iP3, of course!).
I would think that you could use a PCI version of a card like the GeForce2 MX to get around this problem as well, though I don't know if this has been tried.
As well, PowerLeap says that Windows 2000 will not run properly with an FC-PGA Celeron on these systems, and it is probably safe to assume that Windows XP doesn't work properly either. (Apparently Windows 9x/Me are OK. Also, at least one person has been able to get Linux to run on such a setup.)
Another note about XPS D systems, although not processor-related, it comes up a lot so I thought I'd mention it. This system is normally supposed to use PC66 DIMMs for memory. However, the newer PC100 modules are often cheaper now despite having higher speed capability. For PC100 memory to work on these machines, you must update to BIOS version A09, available here. Before upgrading, be sure to read the two readme files included with the BIOS file. Note that there will be no performance benefit to using PC100 memory on this system, because it will only be running at 66 MHz anyway.
Also, these machines list the maximum supported DIMM size as 128MB, for a total maximum of 384MB. However, I have had one report that a 256MB DIMM worked in a D-series machine, so you could put up to three of them in for a maximum of 768MB.