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A comment on PCIe trouble with 4TB Crucial T500 NVMe SSD for >1 power cycle on MSI PRO X670-P. Parent comment

Re:PCIe trouble with 4TB Crucial T500 NVMe SSD for >1 power ... by LeifCarrotson on Friday December 27, 2024 @11:41PM (#42528642)
And by "the board" I trust you mean the MSI PRO X670-P WIFI motherboard.

There's nothing incorrect about the behavior of the SSD when it's being operated outside the prescribed voltage and power thresholds.

If there's a trickle (and to be clear, the 5V at 300 mA available from an HDMI cable is a trickle for a full motherboard) of current into the 3V3 bus on the ATX connector, something will be the very lowest PMIC to turn on. It's just that on this system, the SSD was the first thing. If anything, the SSD will probably be highly tolerant of brownouts because its LDO will run at around 1.9V.

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Re:PCIe trouble with 4TB Crucial T500 NVMe SSD for >1 power ... by hulitu on Saturday December 28, 2024 @01:59AM (#42529165)
> There's nothing incorrect about the behavior of the SSD when it's being operated outside the prescribed voltage and power thresholds.

It shall set itself in Reset state.

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Re:PCIe trouble with 4TB Crucial T500 NVMe SSD for >1 power ... by LeifCarrotson on Saturday December 28, 2024 @08:41AM (#42530993)
That would be nice, in practice, the SSD requires its power rails to start up in a particular sequence and with very particular voltages.
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Re:PCIe trouble with 4TB Crucial T500 NVMe SSD for >1 power ... by shadowpho on Saturday December 28, 2024 @12:09PM (#42532462)
Only few devices are actually able to do that. Vast majority require require proper voltage sequencing, because to do otherwise is to add cost to your IC
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Re:PCIe trouble with 4TB Crucial T500 NVMe SSD for >1 power ... by Dylan16807 on Saturday December 28, 2024 @02:17AM (#42529227)
> There's nothing incorrect about the behavior of the SSD when it's being operated outside the prescribed voltage and power thresholds.

I'd put some more emphasis on "when", though. If it never comes back when power comes back that's not particularly correct.

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Re:PCIe trouble with 4TB Crucial T500 NVMe SSD for >1 power ... by crest on Saturday December 28, 2024 @07:34AM (#42530619)
That's because if this theory is correct from the point of view of the SSD there was no reboot yet, because there was never any total power loss.
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Re:PCIe trouble with 4TB Crucial T500 NVMe SSD for >1 power ... by Dylan16807 on Saturday December 28, 2024 @08:33AM (#42530937)
It handles warm reboots without power loss just fine, so it deciding now it needs to wait for power loss seems like a flaw.
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Re:PCIe trouble with 4TB Crucial T500 NVMe SSD for >1 power ... by wtallis on Saturday December 28, 2024 @09:34PM (#42536928)
If the SSD reacts to the start of a brown-out with supply voltage dropping way below spec as a signal that an unplanned power loss is happening, then it may do an emergency flush and shutdown that leaves it simply waiting for power to finish dropping to zero. It makes at least some sense for the drive to not try to wake up from that state without a clean power cycle.
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Re:PCIe trouble with 4TB Crucial T500 NVMe SSD for >1 power ... by Dylan16807 on Sunday December 29, 2024 @12:21AM (#42537759)
I think "makes at least some sense" and "not particularly correct" can be true at the same time.
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Re:PCIe trouble with 4TB Crucial T500 NVMe SSD for >1 power ... by smileybarry on Saturday December 28, 2024 @10:22AM (#42531661)
It should still handle PCIe probing and (logical) reconnection without a reboot, though, e.g.: PCIe redirection for a VM.
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