We recently purchased and replaced a motherboard for the Optiplex GX270 from Dell because it would not boot. However, it still does not boot. When the power button is pressed the fan comes on briefly then immediately turns off. We then swapped out the fan thinking that was the problem instead but with the same results. We put the power supply we thought was bad into another machine and it works fine. Anyone have any suggestions about what else the problem could be besides the new motherboard we just purchased and used???
Thanks for your help.
P.S. I am a computer technician for a school district and have replaced motherboards, etc. successfully in the past.
Thank you so very much for your suggestions. After going through it again we removed the CPU and found that one of the pins was broken. We replaced the CPU (the mundane part) and it booted fine.
Once again, thank you very much!
Have you tried doing a "breadboard" type test; i.e., remove the motherboard and power supply, place them on a non-conductive surface, connect the power supply, keyboard and monitor, and see if the system will power on? I had a weird situation once where a motherboard standoff had a burr on it that shorted out a new motherboard. It turned out the burr came from a copper trace splash created when lightning ran in on the modem and fried the original motherboard.
Yesterday, I replaced an eMachine motherboard, connected monitor, PS2 mouse, and PS2 keyboard. System would not come on. I noticed that the keyboard lights didn't flash. Disconnected the keyboard, pressed the power button and the system came on. Turned out the doggone keyboard cable was shorted. Since the BIOS uses the keyboard port to initialize the bootstrap loader, the shorted keyboard cable was in effect preventing the system from powering up.
Years ago, I had a Kaypro 16 portable computer come in that wouldn't power up. Removed power supply. It tested fine. Reinstalled it, but only used one mounting screw to secure it. System powered up fine. I assumed the motherboard had discharged some type of static glitch, inserted the other 3 screws and began to tighten them down. When I tightened one of the screws, the system shut down. Loosened the screw, it powered up. Opened the power supply and found a resistor on the power supply board was bent over just enough to touch the mounting screw when it was securely seated.
Of course, your problem may be something more mundane such as a defective CPU or memory stick.
Let us know what you find.
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