Wyse 9450XE: Motherboard 




In February 2016 I had an email from Eric Rucker on the topic of the EPIA motherboard fitted to the Wyse 9450XE.

EPIA Motherboard and clocks

One thing I'd like to add, regarding the Wyse 9450XE (and presumably 9455XL, as it's the same board in a larger chassis) and its firmware, is that Wyse is actually not running stock clock speeds on the EPIA-5000AW.

EPIA boards of this vintage have jumpers that set the FSB frequency - usually 66MHz, 100MHz or 133MHz. (Hence SDRAMs of that era being PC66, PC100 or PC133 speed ratings). This clock is fed into the CPU where it is multiplied up to produce the CPU clock frequency. In some CPUs the multiplication factor is fixed, in others it is programmable. With the VIA CPU on this board it is programmable and on reset defaults to x4.0. i.e. with a 100MHz FSB the CPU would run at 400MHz, with a 133MHz FSB the CPU would run at 533MHz. [*]

On this motherboard the jumpers that set FSB frequency are located between the CPU and the DRAM slots.

CPU clock jumpers

Looking at the board with the edge with the DRAM slots closest to you, you have jumper 1-2 to your left through to jumper 7-8 to your right. If nobody has altered anything you should find jumpers located in positions 3-4 and 7-8 as shown in the photo. This sets the FSB to 100Mhz.

The valid configurations for the jumpers are:

The Wyse BIOS sets the CPU multiplier to 5.5 to get a 550Mhz CPU running with a 100MHz FSB.

I found that setting the FSB to 133 MHz worked whilst in the BIOS screens, but once moving on to booting the OS (Windows XP in my case) my machine fell over and immediately rebooted. The boot summary page showed that it was running with a CPU clock of 733 MHz, as you'd expect from running at 5.5 x 133.

If you flash the BIOS to VIA's BIOS, with the FSB set to 100 MHz you'll notice that your "550 MHz" processor is suddenly running at 400 MHz. That's because it's not really a 550 MHz processor at all, it's just a 533 MHz processor that Wyse slowed the FSB down on, but then cranked the multiplier up from 4.0 (which is what the CPU goes to when reset) to 5.5 in the BIOS.

So you've got a number of options here:

Leave things as they are with the Wyse BIOS. You get a CPU running at 550MHz with a FSB running at 100MHz.

Replace the Wyse BIOS by VIA's standard BIOS and set the FSB jumpers the 133MHz position. You get a CPU running at 533MHz with a FSB running at 133MHz.

What you're looking at here is a trade off between clock rate and FSB speed and one of the combinations may suit your particular workload better than the other.

If you want to compare and contrast the two options - or try other combinations - you can actually do this by flashing the board with VIA's BIOS and using a software tool that will let you change the multiplier. The website has an old version of WCPUID, the tool that lets you change the multiplier on VIA CPUs. (NB WCPUID is a Windows application). This can be found here.


[*] In fact the situation is a little bit more complicated than this. For those with an interest I suggest you look at the VIA VT8601A/Apollo PLE133 datasheet. This includes the following table which shows various configuration options:

CPUDRAMGUI CoreInternal AGPPCIComments
133 MHz133 MHz100 MHz66 MHz33 MHzSynchronous (DRAM uses CPU clock)
133 MHz100 MHz100 MHz 66 MHz 33 MHzPseudo-synchronous (DRAM uses GUI clock)
100 MHz133 MHz100 MHz66 MHz 33 MHzPseudo-synchronous (DRAM uses GUI clock)
100 MHz100 MHz100 MHz 66 MHz 33 MHzSynchronous (DRAM uses CPU clock)
100 MHz 66 MHz 66 MHz 66 MHz 33 MHzPseudo-synchronous (DRAM uses GUI clock)
66 MHz100 MHz100 MHz 66 MHz 33 MHzPseudo-synchronous (DRAM uses GUI clock)
66 MHz 66 MHz 66 MHz 66 MHz 33 MHzSynchronous (DRAM uses CPU clock)


Any comments? email me.    Last update February 2016