Board:
Symptoms:
Things ive tried:
Things I havent tried:
According to the Power up sequence if power is getting to the RESET pin, then it would have completed its power sequence. Now the question is, what is causing it to cycle the power? is it a bad read on the PCH or CPU? (none of the pins seem damaged)
- GIGABYTE GA-H81M-DS2 REV: 3.0
- I have a working GA-H81M-S1 REV: 2.0 here for Comparison,
- CPU is a Pentiium G2220 for testing purposes
- Ram is 1600MHZ G skill 4gb pc12800
Symptoms:
- Motherboard cycles its power sequence regardless of whether there is a CPU AND/OR RAM installed. The working board stays on when powered with no CPU and RAM.
- NO POST messages received from plugging in the POST card into each of the PCIE 1x SLOTS
- Tested all the main power rails and voltage responses to the SIO chip reading normal
- Power is reaching the RST + Pin for the reset switch and PWR switch
- BIOS chip has been removed and reprogrammed with the latest GIGABYTE version bios VIA the CH341A china flasher.
- With the CPU 12v connector removed it will power on and shut off without looping.
- Jumping the POWER on at the ATX connector will keep the board in a powered state, nothing seems to be abnormal, PCH heats up normally, CPU Does not heat up. All the main power rails are present with corresponding voltages.
Things ive tried:
- Ive checked the power going into the power controllers and PCH hub and they all seem to be the same, the resistance i thought was low on the 3.3v rail (12.7Ohms) was exactly the same on the working board, the PCH is getting its 3.3v and 1.04V
- I have also swapped the bios chips, desoldered and loaded the latest firmware onto them. but still no luck.
- Tested the resistance on the coils on the cpu Vcore on the good one it climbs right up to 180k ohm and the bad one goes to about 140k but not sure exactly because it keeps climbing slowly.
- Booting with or without CPU+FAN and RAM makes no difference.
Things I havent tried:
- I dont have an oscilloscope so i havent been able to check the Crystal for clock generation.
- Checking the 25mhz clock generation built into the PCH chip.
- PCH gets pretty warm when
- All the VRIN inputs to the SIO chip read around 2.0 to 2.7v which i guess high means present? I havent checked every single resistor and capacitor around the chip for faults, I only did a quick check according to the picture attached with the main 3.3v in and voltage sense values.
According to the Power up sequence if power is getting to the RESET pin, then it would have completed its power sequence. Now the question is, what is causing it to cycle the power? is it a bad read on the PCH or CPU? (none of the pins seem damaged)
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