Replace CPU on motherboard. Now it won't boot?

Actually, it might be the power supply after all, because i see nothing wrong with the mobo and the front panel is working, so if it is... can anyone recommend me a replacement power supply?

Are you sure the new CPU is the right socket type and is compatible with the motherboard? Usually prebuilt computers have a very limited upgrade list. The CPU has to be the right brand ( AMD or Intel) right socket type and right TDP or it won't work.

1: Curious, did you run the BIOS firmware update when you had your original CPU hooked into it and the computer turned on and ran fine after that prior to installing the new processor?

2: When you try to turn it on, does the power supply fan spin up but nothing is displayed on your screen then?

3: Do you get any beep error codes? Dell computers will spit out a beep code if not working correctly. Tell us what the beep codes are please. You should be able to turn the power on your computer without any memory installed and it will freak out with a beep code. There are beep codes for non-working, non present CPU's, No Video Cards, bad/missing RAM etc.

TRY THIS: Strip your comptuer down to the bare requirements, as in motherboard, CPU and memory. So if you have multiple sticks of RAM, take them all out except for one. unplug any external devices, Printers, hard drives, keyboard and mouse etc.
This means unplugging hard drives (your computer can POST without any HDD, it just cannot load the OS), any PCI/PCIe cards. With this basic config, if it works you will still be able to see the display on the monitor (because this, along with the power cable, are the only things plugged into your Dell computer).

So See if your computer turns on like this, If not are you getting a beep code this time?

Try a different stick of RAM and see if this changes.

I know you said you switched your Processor back to the original, but go back and re-seat this CPU, as in remove heatsink, take out the CPU and put it right back in.

4: Have you tried to reset your system BIOS via the jumpers? If your system is trying to use manually configured FSB/Multiplier settings, they may not work with your new Quad CPU (i know that this would go away when you put the original CPU back in but check anyway) If your dell does not have a jumper, you can disconnect your power cable and pull out the CMOS battery and leave it out for a bit and then put it back which will reset your BIOS.

If you do get a display now, Start to re-connect your internal devices such as the hard drive, keyboard, mouse one at a time and if you get to a device that prevents the computer from POSTing, then you have your cuplrit.

answer those questions and let us know the results.

1. Yes it ran fine with the original CPU, i updated like a year ago.

2. I think this may be the cause. I tried the paper clip trick and shorted the green and black cables, fans did not power on. Guessing the power supply is fried.

3. No beep codes. Just blinking amber. The only possible reasons for this is the PSU.

Can you get power supplies via best buy nearby or only online?

Yes but they're going to be pretty junky. It might not be bad to get a cheap one just for testing but I wouldn't depend on a cheap 40 dollar Antec to power my computer.

So if the power supply is not turning on, odds are that is the culprit, but did this system ever boot with the new q6600 chip? you made it sound like it stopped booting after you installed the new chip which would make the PSU stopping to work at that exact moment very curious.

If you cannot trigger the PSU to spin up with the jumper method of the green and ground wires, then obviously the PSU is done, unless you happened to switch the 115/230 voltage trigger on the power supply. In the US, if you switch off of the 115, it shouldnt wreck the PSU, it just wont power up due to insufficient power from what its expecting. And it would now power up with the motherboard or your jumper trick. So give that a lookie see.
So I've also seen a problem exclusively with Dell computers, where the system wont turn on and after we replaced the motherboard and power supply it turned out that the simple front panel switch was the problem as the power button, though it felt like it was toggling the switch, was actually stuck down.

Look at this: http://support.dell.com/support/edocs/systems/dimE520/e...
Click on Advanced Troubleshooting:
If the power light is blinking amber, the computer is receiving electrical power, but an internal power problem might exist.

Ensure that the voltage selection switch is set to match the AC power at your location (if applicable).

Actually, on your motherboard, you have the Front Panel connector which facilitates all the switches/buttons/LEDs on the front of the case, With the Dells this is all proprietary instead of labeling them nicely for users to plug in one by one. But anyway i found a link that shows the pinout, so if it is this front panel, you can cross the power switch to jump start your Dell motherboard without this finicky front and control panels.

http://www.lnmdesign.com/400sc/front_pnl.html

Sorry for the prolonged response...but.

I have no clue how this works. Can you tell me which pins on the front panel port am i crossing? You may be right about the front panel being the cause of the issue instead of the power supply.

well on "normal' motherboards" it would be a powered plug connected to a ground i believe, meaning that you could try connecting pin 20 (power) to pin 19 a ground.

I do not believe that you would be connecting power from one panel all the way to the other, im assuming Power switch left side on one panel would be power and then the right side from the other panel of pins would be reset possibly?
I did this exact thing once, but this was about 6 years ago and we didnt figure it out until we replaced the motherboard, CPU, RAM and the PSU! haha

check the motherboard pins under cpu.