Intel DX79TO BIOS POST error code 5A


About a week ago my monitor started going on standby at different times. The only way to wake it up, was to switch power off at the wall and back on again, then restart the computer. It started getting worse until Thursday when nothing I did could wake up the monitor. There were no POST error codes or beeps, the pc worked fine except for the monitor going on standby. On Friday I tried again by switching the power off and on and starting the pc, and now suddenly I get BIOS POST error code 5A, 2 long beeps, a pause and 2 long beeps again. Then the POST carries on and stops at 5b (or S6 or Sb). It is not clear since the monitor does not come on, I can only see the code on the motherboard's display.

I bought a new monitor and connected it to the pc with the same result. I removed all RAM modules and tried different modules in DIMM 1 slot, still the same. Removed one by one the sound card, removed Graphics card, removed all SATA devices: 2 x DVD-Roms and 3 x HDD and 1 x SSD. (one by one and all together). Tried a CMOS reset (removed battery for 20 minutes) and BIOS recovery (removed jumper, restarted, replaced jumper and restarted)

I will be borrowing a Graphics Card from a friend tomorrow to test the card, but since I get the same error code even with the card removed, I do not have high hopes.

Could the cause be a faulty motherboard or CPU and how will I check this without buying new ones (unnecessarily like the monitor)

There has been no changes to hardware, programs or applications. This PC has been the same for 2 years, except the replacement of a faulty Graphics card more than 6 months ago.

Thank you for any help and advice

Motherboard: DX79T0 Lga 2011
Chipset: Intel core i7 2011
RAM: Kingston HyperX Predator 1866 (4 x 4gb)
Graphics Card: Gigabyte Radeon R9 290X Windforce
HDD: 3 x Seagate 2 TB
SSD: 1 x Intel SSD
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  1. Best answer

    So I borrowed a Graphics card from a friend, switched out the cards, and everything is working fine. Switched it back and bleep bleep bleep....

    So in this situation it was the Graphics card gone bad.


    (I have read the postings on how to mark as solved, but there is no choose best answer available in this thread. Can a moderater please mark this as solved or close it?)
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