Processor upgrade

You can't upgrade just the CPU - you'd need to replace the entire system board.  Options below, but compare the cost of a complete, used system to that of a board -- it likely won't cost more and could even be less expensive.

https://www.parts-people.com/index.php?action=category&id=140&subid=1191&refine=motherboard

I have a laptop EZ Pass IL latittude i5 5490. 

How do i know witch processor upgrades it supports?

Hello @user_c7d622,
The Dell Latitude 5490 has a soldered CPU (e.g., i5-8350U), so it does not support processor upgrades. You can upgrade RAM and storage, but the CPU is fixed to the motherboard.

Best Regards,
Delia Guzman