CMOS reset (short jumpers) via switch mounted on case exterior

[boggsie]

I'm looking for pointers on how I might construct a switch to toggle between jumper settings so that I can reset CMOS without cracking the case open?

I could also use this to short the jumpers and adjust FSB speed from a similar, separate switch.

In my case, I am working with a motherboard where:

To reset CMOS, we are talking about a 3-pin header:
If 1 & 2 are shorted, then the CMOS is reset to default.
If 2 & 3 are shorted, then the board operates normally. (probably just a storage position for the jumper)

Similarly, to adjust FSB range, we're talking about a 3-pin header:
- Short pin 1 & 2 to get 100Mhz to 132Mhz range
- Short pin 2 & 3 to get 133Mhz to 1xxMhz range

If 1 & 2 are shorted, then in the BIOS you can adjust from 100 to 132 in 1Mhz increments.
If 2 & 3 are shorted, then in the BIOS you can adjust from 133 to 1xx in 1Mhz increments.

Anyway, I need to secure a source for the headers, pins and a reasonably nice switch. If you have any thoughts, please chime in.

I saw a 'home brew' guide on this a long time ago, but I have been unable to google it.

Best regards,
-boggsie

 

[Concillian]

You want a "Single Pole Double Throw" "ON-ON" switch

Then you hook pin 2 to the center and pin 1 and 3 on the opposite sides. One side will short 2 to 3 and the other side will short 2 to 1.

Look at a place like mouser.

 

[boggsie]

I'll check 'em out. Any thought on a motherboard header to connect to the dip switch pins?

 

[VirtualLarry]

It's kind of sad that such a thing is even required these days. My old Abit BX6r-2 mobo, used to have a form of CMOS failsafe in it, that if you OC'ed too far, resetting several times (or forcing a soft power-off, I forget which), would automatically load "safe" default settings for the CPU config, and you could tweak up from there. My current MSI K4V-L KT400 mobo, on the other hand, is a total PITA, that requires opening it up, and removing a couple of cards, just to move that bloody jumper. It also has a slight tendency to freeze on boot if the CPU parameters are changed too much, all at once.

 

[jbh129]

the chaintech vnf3-250, although ghetto, allows you to re-enter setup if you go to far by just pressing the reset button. It has made tweaking much easier.