Can i replace a power supply for compaq evo D510 with an standard ATX power supply? if its no possible, send me a proper description detailled of connectors (wiring). thinks.

Probably however if you upgrade the motherboard you will have to upgrade the CPU, and the memory, possibly the hard drive if the old board is IDE and the new is sata. Also you would have to upgrade the power supply if it's so old it may not have sata power connectors.

Please try getting into safe mode bt tapping f8 continuously.
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Here you go.

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

Choose within this options with regards to your monitor: 1. You could replace your monitor with a new one. 2. Or you could send someone or send it to a technician to repair your monitor.
Boot Up Problem: 1. Try checking the Power Supply Unit (PSU) if it give out 12Voltz. If not you could replace it with new PSU. 2. Check the motherboard if there are some blown out Capacitors. If there is, send it to a technician to replace it. If none, replace your Processor. That is the defective. That causes the boot up problem.
On boot up screen. Of course it will not show a boot up screen because there is a problem on your monitor. And so, there is also a problem on your motherboard (Processor or Capacitor).
Hope this might help. Thanks.

first problem its a compaq go buy something else no seriously buy something else
check your bios settings F10 for compaq if i remember corectly might be F2
http://h18000.www1.hp.com/products/quickspecs/11349_na/11349_na.HTML

http://reviews.cnet.com/desktops/hp-compaq-evo-d510/1707-3118_7-20719364.html
i mean com on 533 bus and dosnt saport multi core cpu's
my 2004 dell 200 mhz buss saports quad core wth
if its not a bios setting replace your keyboard good luck

the RAM may be corrupted or not properly installed into the slot. also check if the processor fan is working properly.

Here is a link to HP's driver support page. Find your model number and follow the links to get the Network Driver for the appropriate model.

http://h10025.www1.hp.com/ewfrf/wc/prodTopCategory?product=89324&lc=en&dlc=en&cc=us

Contac Compaq/HP in the USA and ask them for help.

Check the power supply unit.