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From searching in google, the only info I could find suggests that the 62YVH is from a Dell Optiplex GX260 and the 02H240 is from an optiplex 150.
If I am correct about this, then the GX260 is a Pentium 4 motherboard and the GX150 is a Pentium 3 (socket 370). However, the best way of determining this is simply to look at the board & see what cpu socket it has. You could also go to Dells website, search for the service manuals (which will include a diagram of the motherboard) for the 2 optiplexes I've listed, and then compare them to the ones you have been given.
There are several different form factors for these boards though - i.e. desktop, mini-tower etc. Some of these use riser cards in order to provide the PCI expansion slots. If you have one of these boards, you will need the riser card(s) to go with it.
Even if you have the riser cards etc, this often means that the board will not fit a standard case. In fact a lot of Dell systems (with or without riser cards) do not standard cases, especially in terms of the rear I/O panel & front panel connectors etc.
You will also find that although many Dell systems will work with memory other than Dells own memory, they do tend to be twitchy about which types of ram they will work with.
Hope this is of some help to you.