So I'm running Unraid 7 on a computer that has been working fine. It is an Intel Mobo with a LSI card in there, with 8 drives on it. It has been working fine for a very long time.

The HDD configuration are all 12TB SATA drives - mainly WDD, but some Seagate, with a 14TB WDD Parity drive. Recently we had an issue with the parity drive failing, so I got a replacement 14TB WDD drive. The replacement drive is almost identical to the original one - both are Ultrastar drives.

When I put the new drive in, nothing. No sign of life on it at all. I can't feel anything in there even giving a hint that it is getting power and spinning up. But if I put the original drive back in there without any changes, it spins up and is recognized.

Out of interest, I put a 12TB drive that I had spare on there to see if I could use that for parity. Again, no sign of power or life on that drive either.

Either I have a really strange coincidence that 2 drives are DOA here and won't power up, or there is something that suggests an incompatibility in there?

Has anyone seen this before? Any thoughts? I changed out the PSU on the box from an 850 watt to a 1000 watt supply, thinking that maybe the thing was being overloaded, but no difference at all.

Is there some subtle difference in drives that work in this config vs. those that don't? The 14tb drive I put in as a replacement shows as being the same, but built 6 months prior. I would have thought that it would at least be an option, but I guess not.

What do you guys do when it comes to replacement drives in this situation? Has anyone experienced this before, and if so what was your solution?

Thanks in advance for your thoughts.

Sounds like a pin3 / 3.3V issue - Some SATA drives use pin 3 to power down the drive.

Fixes include using Kapton tape to cover pin 3 on the drive, or using a SATA to Molex adapter. Search "3.3v pin issue" with Google to get the full story.

You can even cover the first three pins as the first two are not used at all, makes it a bit easier to cut the electrical tape to size. I have 10TB shucked WD Elements drives which I had to tape of the first three pins and then had no issues with them.

On 4/17/2026 at 6:00 PM, ConnerVT said:

Sounds like a pin3 / 3.3V issue - Some SATA drives use pin 3 to power down the drive.

Fixes include using Kapton tape to cover pin 3 on the drive, or using a SATA to Molex adapter. Search "3.3v pin issue" with Google to get the full story.

You guys are all freakin' amazing. Yep, that was it. When I put the 14TB on a Molex adapter, the damn thing showed up. I'm back online. Thank you all!

My friend had been running an Unraid 7 server for a long time without any major problems. The machine had an Intel motherboard, an LSI controller, and eight SATA hard drives, mostly 12TB Western Digital Ultrastar models, along with a 14TB Ultrastar parity drive.

Then the parity drive failed.

Replacing it should have been straightforward. He bought another 14TB Ultrastar drive that appeared almost identical to the original and installed it in the same slot.

Nothing happened.

There was no spin-up, no vibration, and no sign that the drive was receiving power. Thinking the replacement might simply be defective, he tried a spare 12TB drive.

Exactly the same thing happened.

The original parity drive, however, still spun up immediately when put back into the system.

That was when he realized the problem probably wasn't two dead hard drives appearing at exactly the wrong moment.

We started troubleshooting the hardware chain rather than assuming the drives were incompatible. We checked the LSI controller, SATA connections, power cables, backplane connections, drive detection, and whether the replacement drives were actually receiving power. We also compared discussions and documentation from Western Digital, Seagate, and ServeTheHome to understand differences between enterprise drives and their power requirements.

One particularly important detail was the possibility of 3.3V power-disable (PWDIS) on certain enterprise SATA drives. Some drives can refuse to spin up when connected to a power source that presents 3.3V on the relevant pin, while an older drive in the same system may work normally. That can make an apparently identical replacement look completely dead even though the drive itself isn't necessarily faulty.

Before buying another replacement, my friend started checking the exact drive model and power configuration rather than relying only on the capacity and product family. He also compared replacement storage hardware and server components while making sure the replacement drive matched the server's actual power and controller setup.

The mystery finally made sense. The issue wasn't that Unraid suddenly disliked 14TB drives, nor that two manufacturers had coordinated the world's most inconvenient HDD prank. The replacement drives simply behaved differently with the server's existing power configuration.

The experience taught my friend an important lesson about enterprise storage: two hard drives can look almost identical on the specification sheet and still behave differently in a particular server because of firmware, power features, controller compatibility, or connector configuration.

When a replacement drive doesn't even spin up, the first question shouldn't always be, “Is the drive dead?”

Sometimes the better question is:

“Is the server actually giving this particular drive the kind of power it expects?”