BleepingComputer.com: No Boot Devices - Dell

dell dimension 4400, win xp he sp3, lost pwr supply (250W), replaced with ATX 450W 20 pin pwr supply. won't recognize any boot device, no F2, no F8, no signal to the monitor. The new pwr supply has one white wire that the old one didn't have and an on/off switch on the back (still has the 4 prong motheboard connector). Have disconnected all external devices, all power connections, all expansion cards and the memory sticks

poppaken, on Feb 24 2010, 02:34 PM, said:

Im not sure if "lost power supply" was a typo in your post or you ment to say "last power supply"

Did you replace the power supply do to failure?

meant that i lost my 250W power supply and replaced it with a 450W power supply.

ok, I assume then that your 250w PSU bit the dust.

Now we have to figure out here if your former power supply took out the motherboard. What happened with the 250 watt one for you to have to replace it? Power spike? Over heated?

Or maybe you have a loose connection somewhere.

You say you have "no signal to the monitor", so it appears you can't see the BIOSes startup screen.

When you boot up the computer do you hear any BIOS beep codes? If so, how many and to what duration?

You have not provided much info on the PSU you bought, but usually the ATX power cable is all that is needed to power up the motherboard.

Those other connecters are usually for add-in devices like video expansion cards that require direct power from the PSU rather than through the expansion slot.

It might also be a plug for a PSU fan monitor device so the system can monitor and control the PSU fan speed.

What we need to figure out here is if you blew out the motherboard when your PSU failed.

When computer was being powered up, it gave the blue Dell screen. It then rebooted. Powered down and rebooted, while pressing the F2 key. Went into the setup screen, but when I touched the first key on the keyboard, it rebooted. It then never allowed the setup screen again. Tried every way I could think of to reboot: pressed F8, floppy win 98 boot disk, Win xp installation CD. Finally the computer quit recognizing any input devices and the display screen. Had the power supply tested at a computer shop. Bought a new 480 watt (correction to my first info), ATX 20+24 pin switching power supply by LogiSys. Still getting the same results when booting up. Have since disconnected memory sticks, external connections and all internal expansion cards, power supply, and all drives. Also have taken out the CMOS 3 VDC battery and reinstalled.

Incidentally; I hooked everything back up and tried to read the win xp setup cd. Got 3 beeps and nothing happened. The only LED light that I got was the Cd Drive light, which then went off.

This post has been edited by poppaken: 26 February 2010 - 03:00 PM