My PC switch on but restart at boot continuesly and some time shows only blank screen with only motherboard name

[Sherkhanshab]

My CPU switching on but no display ,no beep no response to monitor
After repeatedly 3 times it shows blank screen with my motherboard name(Gigabyte's)

 

[Outlander_04]

New? Old? Hardware list?

 

[Sherkhanshab]

Old PC
Motherboard: Gigabyte's h61
Processor:Intel pentium g630
Ram:4gb ddr3
HDD:250