Precision 7865 - No boot with pcie u.2 carrier

Question

I am attempting to install a pcie carrier card for a 15.36TB Samsung PM1733a U.2 drive, and the system refuses to go beyond POST and behaves oddly.

I can access the BIOS menu (F2) and boot menu (F12), where the u.2 drive is detected correctly, but any attempt to go beyond that and the system LEDs flash once before the power button LED begins to slowly fade in-and-out in white. After 20-30 seconds, the system attempts to boot again and the sequence repeats.

I have tested two different adapter cards (one a direct carrier, one pcie to sff-8643 adapter with the appropriate sff-8643 to sff-8639 cable), and the system behaves the same way. I can confirm both cards work correctly in an Optiplex 5050, where the drive is fully detected and the system boots to the OS without issue.

I have also tested these two adapter cards in all accessible pcie slots in the 7865 (slots 3, 4 and 5. 1 is used by the GPU and 2 is inaccessible)

I can unfortunately find no description of that 'fading' LED pattern in the troubleshooting guides.

The system is updated to the latest BIOS version (1.15.1). Would anyone have any insight?

I know the Precision 7865 also has Flexbay options allowing m.2 drives (SKUs 452-BDWJ and 452-BDWK), but I cannot find information if the backplane also allows u.2 drives like the previous generation of Precision workstation (5820, 7820, 7920) instead of m.2.

mazzinia_ · Answer

Hello, please access the bios and check if there is an option to disable S1 and S3 states, then try to boot ( is a test )

pmeslin · Answer

@mazzinia_​ The closest option in the 7865 bios would be 'Block sleep' in the Power menu, described as 'Enables to block entering sleep (S3) mode in the operating system.' Unfortunately, activating that option made no difference. Still posts and allows bios and boot menu access, but it won't go past that. Even going in the embedded Diagnostics option in the boot menu causes the system to act like it did in my first post.

mazzinia_ · Answer

@pmeslin​ in this case I wonder if there's some incompatibility between the bios and the controller on the U.2 , or if U.2 are not supported. Honestly I would assume being supported, but I kept looking and didn't see it mentioned online in relation to this computer, and the flexbay option for nvme mentions connecting to the 2280 connectors or something like that, but doesn't mention a 2.5' caddy for U.2 . It requires someone from Dell to pitch in, or someone with another 7865

pmeslin · Answer

It's still weird that it detects the drive just fine in the bios before misbehaving. I wasn't sure about the compatibility with the flexbay option either and it's a relatively large expense just for testing, so I'm using a pcie u.2 carrier board.

mazzinia_ · Answer

@pmeslin​ and a pcie u.2 carrier board is pretty much straightforward with nothing in the middle to mess up ( chips ). U.2 drives should plug directly on pcie by design.. only thing is that some brands require drivers that are behind maintenance contracts.So is a bit weird that it's not working. You could maybe cheaply buy one of those adapters you can plug in the minipcie slot for nvme, that offers an out that goes to the U.2 interface and do that kind of test, but I would not bet on the result changing

pmeslin · Answer

@mazzinia_​ Yup, I already have a m.2 to u.2 adapter in transit. The only think I could think of would be something weird about the bios that just doesn't like having mass storage devices on the general pcie slots, but considering there are Dell UltraSpeed Duo/Quad cards available for the 7865, I doubt that's the issue.

mazzinia_ · Answer

@pmeslin​ definitely that cannot be the reason. My bet is something not matching between the u.2 controller chip , it's firmware, and the dell bios of this specific series / the chipset used. Maybe some bios setting for the pci management would do the trick but it's going to be a lot of tests keeping track on changes

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Precision 7865 - No boot with pcie u.2 carrier

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