This processor is 11 years old. The only place you will find a motherboard is on the used market. It would serve no purpose in today's world.
You may find some OLD intel boards here: Motherboard ChipSets Remember, these boards are no longer made. You can also look here: Legacy Intel® Desktop Boards Scroll down till you get to "Legacy Intel® Desktop Boards Products" and manually sift through the list looking for boards.
Any boards, chipsets, and processors of the era you are working with will have no support. For boards made by other manufacturers, you will have to search those manufacturers yourself.
My opinion - you can find lots of those processors on an auction site for as little as $4US. Do yourself a favor and toss the processor in a recycle bin, and spend your time and money on a [much] more current (and supported) hardware effort.
This message was posted on behalf of Intel Corporation
Thank you very much to Al Hill for the information provided above.
In addition, regarding your inquiry, if you can get any of those boards, then you can use either one of them, since the 945G chipset is fully compatible with the Intel® Pentium® 4 Processor 540J processor, on the following link you will be able to verify that information:
Any questions, please let me know.