|"PSU also good i check out with it"|
You checked voltages but that's only semi-helpful. There's no easy way to check that the PSU is capable of supplying the required amperage at those voltages.
"the keyboard that connected to it is not working"
If it's USB & the board has a PS/2 port, try switching to a PS/2 keyboard. Once CMOS is cleared, USB may not work properly until the BIOS settings are reconfigured.
"I even clear the cmos several time (40 to 45 times) of no use"
A board doesn't need a CMOS battery to boot up. All it's used for is to maintain voltage to the CMOS chip so that the BIOS doesn't reset each time the system is powered off. In other words, you can run a system without a CMOS battery as long as you're willing to constantly reconfigure the BIOS settings after each shut down.
"sometime on clearing CMOS I hear 4 beeps(without RAM) and then no beeps at all"
Beeps codes generally indicate the board & CPU are good but as DAVEINCAPS mentioned, the board may have bad capacitors. Sometimes it's not obvious, so look closely.
If you find bad ones & you're good at soldering/desoldering, you might be able swap them out & save the board.