m.2 drive disappears when SATA connected

Vertigo

Vertigo

Vertigo

Soldato
Joined
28 Dec 2003
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Figured this was more likely mobo related than the SSD itself so here goes.

My work machine has an Asus Z370-P mobo which has a Samsung 970 Evo Plus 1TB in the top m.2 slot. It boots and runs from this just fine.

If I connect a standard SATA SSD (860 EVO if it matters) to any SATA connector, then the machine starts booting from this instead (it has an OS on it) but, critically, the m.2 drive vanishes completely.

It's not in the BIOS anywhere. I can't see it, let alone select it as a boot device. If I let Windows boot from the SATA drive, the m.2 is also not visible anywhere in Windows.

Anyone have any ideas?
 
Sounds like they are sharing resources. I would firstly update the BIOS then read the FAQ on the mobo page. Could be a setting/jumper or maybe you have to plug SATA into a specific port.
 
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I could understand if using the m.2 slot disabled one or two SATA interfaces but all of them?!

Actually, thinking about it, that's the wrong way round, it would be the SATA interface disabling the m.2 slot which I've never heard of.
 
If its not detecting in the BIOS then you need to poke about but more than likely a BIOS issue. What version are you on as the latest is 2401 released mid July?
 
Not sure tbh, the machine was new around July last year and I've not updated the BIOS. When it comes to work machines I tend to subscribe to the "ain't broke, don't fix" philosophy.
 
Have a dig through the BIOS/EFI settings. On my Asus Z97 board (couple gens older obviously) it took me a long time to figure out why the M.2 wasn't working. It was because on that board, you have to configure it to bump one of the PCIe lanes ( the 4x I think it was?) down to 1x to free up lanes for the M.2. This was hidden in the depths of some advanced settings page. I don't know about your board specifically, but perhaps where that bandwidth comes from is configurable.
 
This is nuts. Even when booting from the m.2 drive (with no SATA SSD connected), there's no sign of it in the BIOS.

The only place it shows is as a boot option in brackets after "Windows Boot Manager" or some such.

If I look at the "PCH/Storage" options, it lists the four SATA connections then has the second M2_2 slot listed (with nothing connected). The main M2_1 slot is nowhere to be seen.
 
Had a friends build with an MSI motherboard where when the board was in UEFI mode not Legacy the m.2 would not show up at all, he had to have the drive set up as GPT for it to show and boot. Otherwise it would just try to load from his old SSD which was MBR. So might be something to do with Secure Boot or Compatability Support Module, might be named differently depending on what board you have.
 
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