Boot problem this is a compaq d510 SFF, it doesn't boot but board gives the yellow light, and power led lights red. what could be the problem?

desktop small form factor, SFF, (not silly fat frog)
no statement as to where lamp is, I'll guess, FRONT.
just the light bothers you, only..?
why not RTM read the manual to learn what it means.?
so where is said LED lamp, ? front of case on the SSF case?
HP calls it, and searches only work with this.
HP Compaq 8000 Elite Small Form Factor PC./
im reading your manual now for you at HP.com
my guess is lamp 5, (pwr) is not green now but is red
green means power ok, red means, not ok.,
page 2:
if flashing , the flashes are codes, what is your flash code if flashing
if not this LED then say which one?
green on 5 means ok. power ok, no errors. red bad.



http://h10032.www1.hp.com/ctg/Manual/c01957825


the flash codes are here. page 47 ,

http://h10032.www1.hp.com/ctg/Manual/c01960471

you stumped me, the service manual shows no steady red.
why not ask at Hp.com

more manuals here
https://support.hp.com/us-en/product/hp-compaq-8000-elite-small-form-factor-pc/4065894/manuals


hp forum here.
http://h30434.www3.hp.com/

yes it should but it could also be hdd or memory or processor or the led are connected wrong on the mother board so I suggest that you take your time and pull down that pc and make sure you follow the necessary safety precautions and look at the mother board and fit it up slowly ok

Power Supply.

Weak voltage power rail, or more than one.

(There are three power rails for the Power Supply used in your computer;
1) The 3.3 Volt power rail
2) The 5 Volt power rail
3) The 12 Volt power rail.

Wires with Orange insulation carry 3.3 Volts
With Red insulation carry 5 Volts
With Yellow insulation carry 12 Volts.

Each wire is connected to one power rail in the Power Supply.
{All Black wires are Ground wires}

The Power Supply in your computer is an SMPS. Switched-Mode Power Supply,

http://en.wikipedia.org/wiki/Switched-mode_power_supply )

I don't know what form factor your Power Supply is because you didn't state which model it is.
Small Form Factor (SFF)
or
Convertible Mini-Tower
or
Ultra Slim Desktop

Post additional questions in a Comment. Also state what model your Compaq Evo D510 is.

Regards,
joecoolvette

PLS REMOVE THE POWER CORD AND THE BATTERY FROM YOUR LAPTOP AND WAIT FOR 5 MINS THEN RE-INSERT THEM AND ON IT . SHOULD WORK

. PLS REPLY OR COMMENT. THANKS

Try to do a Hard Reset. Disconnect all peripherals connected from the unit (power adapter, monitor, keyboard, etc) then press and hold the power button for around 15 seconds. Plug everything back then power the PC on.

Hope this help. Goodluck!

here is what you should have. you cant mix mem types. you are suppose to have what is listed below. maximum amount is 2 gig. have to be pc2100 which is ddr-266

Compaq Evo D510 CMT 2GB Memory Ram Kit (2x1GB)

2GB DDR-266 (PC2100) Kit (2x1GB

Clean your System Board using air blow.. :)

open the machine up and locate the BIOS battery. it is a small round flat battery. take it out for 20 mins and then put back in and try starting up again

hello...remove the memory then make clean and take it back then to boot the unit..Good Luck and Have a nice day..^_^

Check the power supply unit.