Trying to install new motherboard. Failing

I'm fairly certain I installed my new Asus M5A78L-M LX3 motherboard correctly. When I plug in the power cord to my PSU and flip the switch the green LED on the mobo comes on. But when I press the power button nothing happens. At all. The LED on the front never comes on, I don't hear a beep(I don't have a little speaker thing installed. Didn't on my last one but I heard beeps. I had a little speaker thing but I can't find it. Still though. Nothing happens at all.

I know I didn't damage my CPU, I've tried uninstalling both rams, just one, then the other, changing slots, ect.

Only thing I know I did "wrong" was my heatsink for my AMD Athlon II x4 645(maybe not the exact model. It's 3.1Ghz though) didn't fit the motherboard. It's a circle fan with the screw holes in a square pattern. And the bracket that was on the motherboard(I just unscrewed it and took it off with the back plate) is a rectangular one. I'm letting thermal paste(Arctic Silver 5 99.9% pure Silver from RadioShack) harden and glue the heatsink to the CPU until I can get a heatsink that will fit. However I don't see how that would be effecting this.

Any help would be greatly appreciated. I'm at a loss.
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  1. Best answer
    most new mb need more power then 24 pin atx plug there should be near the cpu a 4/8 pin white power plug did you connect that?? also did you use the brass standoff to keep the mb from shorting out??
  2. I have 4 pin plug by the CPU plugged in already. And if by brass standoffs you mean the things you screw into the holes on the chassis, put the mobo on, and then fasten the mobo onto with screws? Got those as well.
  3. Are both power connectors plugged into the motherboard, one with 24 pins, the other with 4 or 8 pins?

    Do you have the power button connected to the correct pins on the motherboard, and does the button and its wiring work? Try briefly shorting the correct 2 pins on the motherboard together with a pencil.

    Beep codes from the speaker can be very helpful in diagnosis. Some speakers won't make any sound when connected backward.

    Some motherboards won't start if the CPU overheats, such as from inadequate contact with the heatsink, which can make it overheat very quickly. Don't rely on thermal paste to hold the heatsink in place, and keep the motherboard horizontal until it can be attached properly.

    Look for a short between the motherboard and case, such as from extra brass standoffs that should not have been installed, screws or standoffs shorting copper traces (fiber washers may be needed), or sagging at corners.
  4. I've followed the diagrams in my mobo manual to hook up the power switch, reset switch, and LEDs. I've checked them again like 4 times. I haven't tried shorting the power ones but I know the power button to my case works. I was using it earlier today.

    I've also checked for shorts already. No screws, standoffs, wires, or anything under the mobo.

    And I planned on keep the mobo horizontal until I get a proper heatsink to fit the bracket things ;P
  5. Just tried shorting it with a pencil. Nothing happened still.

    I'd hook everything back up to my old mobo to check but I don't have a manual for it an I don't know where my power switch plugs in to it(My case has the cords that are all separated. Not just one plug :/ )
  6. Best answer selected by Jassie.
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