It's a Dell case, dude. You can't put a *real* motherboard in it, just Dell crap.
kalrez,
I posted a link to a replacement board. If you wanna pay more for one, go right ahead. A little bit of googling would have given you the answer you need:
"Dell 5E692
Dell Replacement Motherboard for Dell Dimension 8100 Series and OptiPlex GX400 Intel 850 Chipset P4 423 Socket RDRAM BOARD ONLY. DP/N: 05E692 5E692 can also replace Dell P/N: 03F546 3F546 09D307 9D307 03J182 3J182 025REH 25REH"
We're Sorry! No products are currently available for the system you selected. Your system may require proprietary or non-standard parts. If your system requires RDRAM or Rambus technology click here.
This is from crucial.com
If your motherboard is bad I would just follow the advice in Response 1 from jam assuming you need to continue with your present system.
Yes I'm finding a lot of MoBo for the 8100 for $ 25.00 & up some of the used one include the original processor and memory sticks.
Again I really would like to know what the differences are in the numbering system of dell . I am waiting for a answer from a supplier on a board he has listed as 025REH-12405 to see if it is a "MX" (someone said the MX is for the NVIDIA graphics card) and if it is a MX 025REH-12405 I will go for that one less than $ 30.00 plus $ 12.00 shipping. I might even get a couple of different boards and see what if any difference would be, plus I would have future spares and just for the memory alone it's worth it.
This is a computer for my 10 year old son(that is doing HTML code on his own website). And I just enjoy doing repairs/ builds like this with him to learn. When I dig into something like this with various motherboards for the same series computers I just got to Know why, It's the same for almost everything in my walk of life.