Hello, Can i overclock intel dh55pj motherboard on bios? If so, How? hope for your quick response,thank you!

SOURCE: How I can get software to overclock intel processor

if the BIOS does not have the configurations for it, you could try getting a BIOS firmware update, or buying a new BIOS from the company. otherwise it cannot be done.b

SOURCE: overclocking

Overclocking is set from the BIOS configuration. Not all BIOS allows overclocking, it may need a BIOS upgrade.
Check the ASUS WEB site for your model motherboard.
Overclocking the CPU (ie running at a higher clock speed) and increasing Frontside bus speed will give better performance BUT there is a downside too, if you overclock too high you could overheat the CPU and it could fail.

SOURCE: update bios

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SOURCE: how to overclock 945GCT-M2/1333 motherboard

Try getting an overclockers BIOS. ECS motherboards don't usually offer the best overclocking support.

SOURCE: can intel dual core e5400 work on my motherboard?

Yes you can.
Your motherboard is LGA775 socket and supports the folowing processors:
Core2 Duo / Pentium Dual Core (yours) / Pentium D / Pentium 4 / Celeron 4xx series/ Celeron D.