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SM951 not detected after shutdown more than 1 hour
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    Posted: 08 Jan 2016 at 10:23pm
First, I'm new here, so Hi! Second, problem as it says in the title.

I've been building PCs for almost 30 years and I've read a lot about booting Windows from SM951, here and in many other forums. Tried many things, no dice.

Below is the message I sent to Asrock tech support. After a series of emails, problem is not solved. The only new thing I learned in the process is that the problem only happens when the SSD is in M2_1 (the x4 slot), and not in M2_2. They gave up and directed me to the dealer. Before I try to get a new board (or new SM951?), I thought I'd check here if anybody has an idea. Problem also occurs with latest UEFI BIOS (v2.50). Win10 installed with Rufus GPT/UEFI USB stick.

Motherboard: Z97 Extreme6
UEFI BIOS: v2.30, 2.40, 2.50

CPU:

Intel Core i5-4690S

Memory:

2x8GB Corsair Vengeance Dual Channel DDR3-1600

Video Card:

Asus Strix R9 285,PCIE

HDD:

SSD Samsung SM951 AHCI 256GB MZHPV256HDGL

CD-ROM:

,

OS:

Windows 10 64-bit

Other Devices:

Western Digital Black SATA 6Gbps 2TB


- Windows 10 Pro is on the Samsung SM951 AHCI SSD in slot M2_1.
- After normal OS shutdown, if I wait more than ~50 minutes, the system does not boot when I turn it on. The SSD is NOT FOUND, so the Windows Boot Manager is also not found, and the computer goes directly to UEFI main page.
- Problem happens from day 1.
 - UEFI -> Advanced -> Storage Configuration: NOTHING in M2_1.
- UEFI -> Boot -> Boot Option Priorites: NOTHING. Button-menu has disappeared.
- If shutdown has lasted less than ~50 minutes, computer boots normally every time. Extremely rarely, it also boots OK after having been shut down for several hours or days.
- CMOS battery is OK. I've tried two batteries.
- Dr. Debug code: Ab
- After problem, if I press Esc from UEFI main page and confirm "Discard changes and exit setup?", the computer restarts and the OS boots normally.
- Problem happens with default Asrock UEFI configuration. Also happens with my optimal configuration (Fast Boot, CSM disabled, etc.) and with many, many other UEFI setup tests.
- Problem also happened with UEFI v. 2.30.
- When shut down, motherboard still has power, as shown by LED on graphics card.
- Another person described the exact same problem in an Internet forum.
 - Among other things, I will need to use Wake-on-LAN. This problem makes it impossible.

I've tried various things suggested by Asrock Tech Support, but to no avail. The only significant thing was disabling Fast Start in Windows 10, but it didn't change anything.

Dead
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Points: 4996 		Post Options Post Options   Thanks (0) Thanks(0)   Quote parsec Quote  Post ReplyReply Direct Link To This Post Posted: 09 Jan 2016 at 4:32am
That is a very unusual problem, as I'm sure you know.

Coincidentally, I have an AHCI 256GB SM951 in my ASRock Z97 Extreme6 board as the OS drive. I have never had the problem with it that you now have.

Two things in general that are different between our PCs is I am using a Xeon E3-1276 v3 processor, and I am using the integrated Intel graphics. So no video card in my PC.

I'm guessing you are using the PCIE2 slot for your video card? That would mean the SM951 is covered by the video card. Since you did not have the same problem with the SM951 in the M2_2 slot, I wonder if the video card is somehow pressing or interfering with the SM951 in some way. That could be both physically, electrically, or both.

Since we are stuck with 16 PCIe 3.0 lanes from the Haswell processor, and those lanes are shared between the video card and the M2_1 slot. The M2_2 slot uses resources from the Z97 chipset, and not the PCIe 3.0 lanes from the CPU. That might be a clue or related to your problem. I have a suggestion related to that below.

When using the M2_1 slot, the PCIE2 slot is reduced to x8 electrically, since the M2_1 slot uses four PCIe 3.0 lanes.

I considered suggesting putting your video card in the PCIE4 slot, but I am not sure if the PCIE4 slot will operate at x8 when using the M2_1 slot, and the PCIE2 slot empty.

When using video cards in both PCIE2 and PCIE4, and the M2_1 slot occupied, the PCIE4 slot runs in x4 mode. Will the board's logic be smart enough to allow PCIE4 to run at x8 with the PCIE2 slot empty? You'll need to experiment.

Another experiment would be to remove the video card, and see if your problem changes.

My only suggesting directly involving the SM951 is to remount it again in the M2_1 slot. Just in case its connection is not perfect now. You can clearly see how close together the contacts in the M.2 slot are, it's a miracle they manage to stay separate and make good contact IMO.

Your system specs are great, thanks for that but I'm wondering what PSU you are using.
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Points: 4 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Entropist Quote  Post ReplyReply Direct Link To This Post Posted: 09 Jan 2016 at 4:29pm
Thanks parsec. I'm using a Seasonic Platinum 660.

I think I did try to remove the graphics card and use integrated graphics, but I'm not so sure anymore, will try (again). I was aware of PCIE2 going down to x8 when using M2_1, but I never made the link with the problem. Good point. I thought about incompatibility between the graphics card and the SSD, but then again, the "after a while" nature of the problem seems to negate this, unless the electrical state of either changes after a while, then there's a conflict at startup, maybe in a testing phase... Is there a way to get a full, low-level-detailed boot log?

I checked that the SM951 was properly inserted when I plugged it back in M2_1 after trying M2_2.

I will try the graphics card in PCIE4, but I seem to remember that using PCIE2 first is mandatory. Maybe that was in order to get x16, and I'm getting only x8 now anyway.

As of now, I can think of three things:
- Faulty behavior on the SM951 related to its low power standby mode, maybe linked to the state when shutting down or starting up. This seems unlikely, as others would have had the problem. There was one post somewhere a few months back, but I can't find it again.

- Some motherboard component (capacitor? my knowledge of electronics is very limited) gets discharged after a while, even though there's still power when shut down, and something happens on the M2_1 channel (do you think M2_1 is still powered when the computer is shut down?)

- Other hardware default in either board or SSD.
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