RE: yellow light motherboard computer will not boot
LED on motherboard is perfectly normal.
What form factor 780 is this, desktop, tower, small form, ultra-small?
Have you checked the 4 diagnostic LEDs on rear of PC when it won't boot? Look up error code in the manual: downloads.dell.com/.../optiplex-780_service manual2_en-us.pdf
Tried installing a fresh motherboard battery?
Are you sure those RAM modules are compatible with this PC? Have you tested them one at a time in slot 1?
Forum Member since 2004
I am not a Dell employee