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Newly built computer won't turn on. No LED light.

Last response: in Systems
February 12, 2010 8:26:11 PM

Hi there, I've been searching these forums but couldn't find an answer...
I've put together my first pc, followed instruction online and in the manual, but when I connected the power and tried to turn it on, nothing happened. Nothing at all. I had a look inside, and the LED light on the motherboard is not on.
My motherboard is Gigabyte MA 785GT UD2H and the power supply is from my previous PC, which was powering on well...
Many thanks in advance!
a c 207 V Motherboard
February 12, 2010 8:52:16 PM

How many cables going to MoBo ?

Should be the 24 pin cable and the 8 pin EPS cable.
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February 12, 2010 9:07:20 PM

I have connected a 24 pin cable and a 4 pin cable into the 8pin connectors, as per the motherboard instructions...

Have worked through the 21 things on that list... Planning to breadboard now...

Best solution

a b V Motherboard
February 12, 2010 9:34:50 PM

The switch on the PSU in the on position? Did you hook up the case power button correctly?
February 12, 2010 10:33:08 PM

Yes the PSU switch is on. I reconnected all the front panel headers and now, the system and CPU fans are turning on. DVD drive opening, but no beep or display...
February 12, 2010 10:35:42 PM

Thank you for the link to the list. I have gone through it, and only number 20 I have not done yet.

1. Did you carefully read the motherboard owners manual?

Yes, a few times…

2. Did you plug in the 4/8-pin CPU power connector located near the CPU socket? If the motherboard has 8 pins and your PSU only has 4 pins, you can use the 4-pin connector. The 4-pin connector USUALLY goes on the 4 pins located closest to the CPU. If the motherboard has an 8-pin connector with a cover over 4 pins, you can remove the cover and use an 8-pin plug if your power supply has one. This power connector provides power to the CPU. Your system has no chance of posting without this connector plugged in! Check your motherboard owners manual for more information about the CPU power connector. This is easily the most common new-builder mistake.

Connected 4pin to 8pin checked with manual

3. Did you install the standoffs under the motherboard? Did you place them so they all align with the screw holes in the motherboard, with no extra standoffs touching the board in the wrong place? A standoff installed in the wrong place can cause a short and prevent the system from booting.

7 standoffs placed

4. Did you verify that the video card is fully seated? (may require more force than a new builder expects.)

Integrated graphics

5. Did you attach all the required power connector(s) to the video card? (some need two, some need none, many need one.)

As above

6. Have you tried booting with just one stick of RAM installed? (Try each stick of RAM individually in each RAM slot.) If you can get the system to boot with a single stick of RAM, you should manually set the RAM speed, timings, and voltage to the manufacturers specs in the BIOS before attempting to boot with all sticks of RAM installed.

No difference

7. Did you verify that all memory modules are fully inserted? (may require more force than a new builder expects.) It's a good idea to install the RAM on the motherboard before it's in the case.


8. Did you verify in the owners manual that you're using the correct RAM slots? Many i7 motherboards require RAM to be installed in the slots starting with the one further away from the CPU which is the opposite of many dual channel motherboards.

Yes, as per manual

9. Did you remove the plastic guard over the CPU socket? (this actually comes up occasionally.)


10. Did you install the CPU correctly? There will be an arrow on the CPU that needs to line up with an arrow on the motherboard CPU socket. Be sure to pay special attention to that part of the manual!

CPU lined up with arrow on motherboard socket

11. If using an after market CPU cooler, did you get any thermal paste on the motherboard, CPU socket, or CPU pins? Did you use the smallest amount you could? Here's a couple links that may help:

Stock CPU cooler

12. Is the CPU fan plugged in?


13. If using a stock cooler, was the thermal material on the base of the cooler free of foreign material, and did you remove any protective covering? If the stock cooler has push-pins, did you ensure that all four pins snapped securely into place? (The easiest way to install the push-pins is outside the case sitting on a non-conductive surface like the motherboard box. Read the instructions! The push-pins should be turned the OPPOSITE direction as the arrows.)

Yes x2

14. Are any loose screws laying on the motherboard, or jammed against it? Are there any wires run directly under the motherboard? You should not run wires under the motherboard since the soldered wires on the underside of the motherboard can cut into the insulation on the wires and cause a short. Some cases have space to run wires on the back side of the motherboard tray.


15. Did you ensure you discharged all static electricity before touching any of your components?


16. Did you install the system speaker (if provided) so you can check beep-codes in the manual? A system speaker is NOT the same as normal speakers that plug into the back of the motherboard. A system speaker plugs into a header on the motherboard that's usually located near the front panel connectors. If you case or motherboard didn't come with a system speaker you can buy one here:


17. Did you read the instructions in the manual on how to properly connect the front panel plugs? (Power switch, power led, reset switch, HD activity led) Polarity does not matter with the power and reset switches. If power or drive activity LED's do not come on, reverse the connections. For troubleshooting purposes, disconnect the reset switch. If it is shorted, the machine either will not POST at all, or it will endlessly reboot.

White and black are negative. Colours positive.

18. Did you turn on the power supply switch located on the back of the PSU? Is the power plug on a switch? If it is, is the switch turned on? Is there a GFI circuit on the plug-in? If there is, make sure it isn't tripped.


19. Is your CPU supported by the BIOS revision installed on your motherboard? Most motherboards will post a CPU compatibility list on their website.

Athlon II is listed on the box, so I assume so.

20. Have you tried resetting the CMOS? The motherboard manual will have instructions for your particular board.

Is this the CLR_CMOS (Clearing CMOS jumper)?

21. If you have integrated video and a video card, try the integrated video port. Resetting the bios, can make it default back to the onboard video.

February 12, 2010 10:52:47 PM

Another interesting thing is that even when I take both(all) the ram out, I get no beeps... does this mean my motherboard has a problem?
February 20, 2010 4:13:53 AM

Best answer selected by DRJK.