Without using the Processor, how to know if the motherboard is working. For eg if i connect the power supply and the cpu fan and smps fan is running, power good led is on and connected keyboard leds are working, does this mean motherboard is fine?
You can't. The CPU contains a lot of important parts for controlling parts of the board, eg. the memory controller is on there (for most current x86 CPUs, at least). Without a CPU, most of the board will not even get initialized.
Even with a CPU, you will not really be able to tell if a board is working fine just by looking at some status output. Lots of hardware faults just show up by weird behavior during normal work. But you probably will be able to find most of them by booting the computer once, and maybe running some burn-in tests.