Background of the question:

My PC no longer POSTs; no sounds and lights appear at all (I.e., no reaction whatsoever after pressing the power button).

I want to isolate the component that is likely to cause the failure (most likely PSU because my PC would only wake ~5% of the time from sleep in the last 2 months, the PSU is >7years old, and is from merely a moderately reliable vendor).

CPU, Motherboard and RAM are very unlikely (they never made a sign of degradation, aren't overclocked, and come from the most reliable consumer vendors).

In this question, I would like to exclude the GPU and GPU drivers (the issue happened after updating the graphics driver, but the failure is likely independent) from consideration.

My main questions that allow me to exclude the GPU and the GPU driver from the overall problem:

  1. Does the boot start of a PC (POST) use:

    A. the discrete GPU to render the black-and-white text? or

    B. the graphics processor included on the Intel CPU? or is

    C. another processor used for the rendering of the POST text (the actual CPU or a motherboard chip)?

    This is assuming that the BIOS has been previously set to use the discrete GPU over the Intel CPU on-chip-GPU.

  2. If the answer to Q1 is A, does the graphics driver installed on the boot disk have any effect on the functionality of POST?

  • If there's no indication of activity at all, it's most certainly a more major problem. And no, graphics drivers on Windows aren't relevant. – Daniel B Sep 27 '15 at 7:28
  • Thanks for the comment. A more major problem relative to what? Relative to the GPU I can see, but relative to the PSU, I'm skeptical: If the PSU is defective, I see no reason for it to power on itself or anything that it's connected to. – Wuschelbeutel Kartoffelhuhn Sep 27 '15 at 7:56
  • Its a power issue if there are no signs of life, it could be anything in the power section of the motherboard. In electronics there are rarely signs of degradation, a small component on the motherboard can fry instantly at any moment causing this issue. Or it could be a defective power button. – Moab Sep 27 '15 at 13:00
  • Do you think the motherboard being the culprit is more probable than the PSU? – Wuschelbeutel Kartoffelhuhn Sep 27 '15 at 14:12
  • Q1 -- The PC will use the video adapter that is configured in the BIOS as the video interface. So it could be either the the discrete GPU or the integrated one. You could try powering off, removing the discrete GPU, and for good measure, remove the battery and reset the BIOS configuration. "Do you think the motherboard being the culprit is more probable than the PSU?" -- Probabilities are too close for choosing one over the other. Parts substitution is the most practical method of troubleshooting/repair. – sawdust Sep 28 '15 at 0:38
  1. Depends on the adapter connected to the monitor (and the adapter selected in the BIOS). In this case it was the discrete GPU.
  2. No

Side note: In this case the culprit turned out to be the PSU.

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