dell e521 will not boot up yellow solid light

[Irene_319]

will not start up. just a yellow light instead of a solid green

 

[Phillip Corcoran]

Different Dell model to yours but same applies: http://www.tomshardware.co.uk/forum/6230-2-orange-light-dell-gx270-power-button

 

[saywhut]

It's either your PSU or motherboard more than likely.

Page 51 of the manual here says it's your PSU/mobo:
http://downloads.dell.com/manuals/all-products/esuprt_desktop/esuprt_dimension_desktops/dimension-e521_service%20manual_en-us.pdf