2 front intake chassis fans won't attached to MOBO

That still won't do all you ask.

First, you say that the fans each have two wires coming to them. That means there is no third wire to carry the fan's internally-generated speed signal anywhere. So even if you use an adapter to plug the fans into a mobo port, you will not be able to read their speed.

If you do the adapter / mobo port thing you MIGHT be able to control the fans' speed. It can work only if the mobo port you plug them into is 3-pin port. The speed of a 3-pin fan is controlled by varying the voltage supplied to it from the port, and that would work on your fans. However, a 4-pin fan receives a constant full 12 VDC on its main power supply line, and then gets an additional signal called PWM that is used inside the fan to set the actual speed. Your fans can't do this, so they will only run at full speed always if connected to a 4-pin mobo port. That is no different from what you have already.

By the way, the best way to do this with a 3-pin mobo port would be to use an adapter system that allows you to connect TWO fans to that one mobo port. This can be done with 2 adapters - one to connect from a mobo 3-pin port to a fan's larger 4-pin Molex connector (the ones that now plug into a PSU output connector), and the second that converts one 4-pin Molex PSU output connector into two of them, so you can plug both fans into that. (You nay already have that second adapter.)

Two other notes to take into account. One is that the lights on the fans are set up assuming they will receive the full 12VDC being supplied to the fan motors. If you power them instead from a mobo port at reduced voltage, the lights may work oddly. The second is the some mobo fan controller systems monitor the fan speeds and warn you (or even take corrective actions) if the fan is not working. When you plug these fans into the 3-pin mobo port but they cannot send a speed signal back to the mobo, the mobo will think those fan(s) connected to the port have failed. You MAY have to tell the mobo fan controller for that one port to ignore the fan speed so it does not throw error warnings at you.

WOAH! LATE THOUGHT!
You say there are TWO wires from the fan(s) to the front panel, where there is a button switch to control the fan lights. Is it true that the fans and the lights are controlled separately? You can turn off the lights while the fans keep running? Then those two wires you traced may ONLY be for the lights. You may NOT have found the fan motor wires which may be separate. Look again and tell us what you find. In the meantime, do not proceed with what I said above until we can verify the fan motor wiring.