Purchased a hp z840 on ebay with a locked bios. Question on this

[Tony_atfpodcast]

No it does not the drives do not power up.  this is the connector to the 3.5 bays and the data is connected to the sata ports. I cant find where the power molex is or connects to  to check if it tor loose 

[SDH]

AI says:

The HP Z840 uses a proprietary cable assembly for its drive bays, rather than standard power supply (PSU) cables. The power and data lines are integrated into a single cable that connects directly from the motherboard to the drives. The specific cable is part number 647109-003. 

The Z840 hard drive power cable connects multiple SATA devices to a single port on the motherboard. A full pinout diagram for the custom cable is not publicly available, but the connection scheme is as follows: 

• Cable Assembly (HP P/N 647109-003): This is a single assembly with a custom connector on one end that plugs into the motherboard and separate connectors for power and data on the other end that connect to the hard drives.
• Motherboard connector: The cable plugs into a proprietary, flat connector on the motherboard, not a traditional Molex or SATA power connector from the PSU.
• Drive connectors: The cable assembly branches out to provide multiple SATA power and data connectors for the four internal 3.5" drive bays. 

SDH says:

Same concept for the Z640 HDD bay. If the motherboard end  of those SATA data and SATA power feeds are disconnected then the drives inserted into each bay can't work. There are separate SATA data plugs and s single SATA power plug that you can check to ensure they're all connected properly.

Also, your SATA HDD or SATA SSD drives should all be DiskPart cleaned and GPT partitioned and NTFS formatted. Ideally you'll be using a HP Z Turbo Drive G2 PCIe card containing a 1TB high quality NVMe M.2 SSD as your boot/applications drive.  We've posted in here on how to use DiskPart, and what PCIe socket the boot ZTD G2 should be inserted into, and also you can run the latest W11 25H2 in that workstation with help from Rufus (now up to version 4.10).

[Tony_atfpodcast]

I just showed you a picture of the part I just don't know where it is connected to the motherboard for power, that is what I'm trying to find out. The data is connected. If I had hair I would be pulling it out  lol 

[SDH]

That part is for the Z800... old wrong part. Right part is 647109-002. The link below should help, plus some search terms for you:

Hard Drive Cable Assembly For Z840 WorkStation

HP Z840 4 BAY 3.5" SATA/SAS HARD DRIVE INTERFACE CABLE

HP Z820 Z840 Cable Assembly Hard Drive Power SATA Data 647109-002

HERE 

You want to go in about 59 minutes on this HP video and start watching there. A lot of added value is present throughout. Here's the table of contents:

What you need...

[Tony_atfpodcast]

Thank you.  They are going to send me a replacement of the same model. I just got an email from them.

[SDH]

Tony,

Attached below is a PDF on use of DiskPart to prep your drives. You can run DiskPart on the drive in any computer... it is part of the operating system. Be careful... make sure to use Disk Management to understand exactly your drive numbers and their size so you don't pick the wrong one.

I've changed over to almost never using MBR... GPT for modern operating systems gives so much more reliable results and experience.

[DGroves]

these hard drives were they pulls from a ext usb drive enclosure? if so some of these drives need to be modded to work inside a normal pc system by covering one of the 3.3v pins on the drives edge connector 

https://www.instructables.com/How-to-Fix-the-33V-Pin-Issue-in-White-Label-Disks-/

https://www.youtube.com/watch?v=IeUWUVH1D20

Edit: (same day)

i doubt you have a defective internal drive harness you can confirm that by inserting a RETAIL 3.5in sata drive that did not come out of a external usb enclosure and i'll bet anything the drive powers up and is seen in the bios

FYI, the four internal hotswap bays power lead does not connect to the motherboard rather it goes on the right side of the case and connects to a molex connector and that wiring goes up to the power supply connectors that engage the actual power supplies edge connectors you would need to remove the right side cover to expose the 4 main wiring harnesses that run from the power supply to the motherboards power connectors

see the HP z840 service manual for details i previously linked to

to remove the right side cover

at the bottom of the right side cover will be two small holes with the covers securing screws remove them and then tap on the top of the right side cover to push the cover downwards (lay the case on it's side)

[Tony_atfpodcast]

No, these are regular drives and SSDs.  They are sending me a replacement unit that arrives today.

[DGroves]

are the internal hotswap bay drives data leads connected to the SATA ports or the white LSI SAS/SATA ports along the bottom of the motherboard

[SDH]

I believe DGroves is ready to get you the solution. The drive bay leads can be plugged into multiple places, depending on who messed with the motherboard attachments in the past. Below is a Z840 motherboard picture and the corresponding HP motherboard diagram. YES is the four gray ports where your SATA SSDs or SATA HDDs should be attached. NO is the 8 bottom white ports where your SATA drive bay leads may currently be attached (and causing the problem):

These 8 series workstations are more complex than the ones we use (4 and 6 series) but I'd say you have the forum's expert's help on 8 series versions, from DGroves now.

White is NO; gray is YES...

Use YES, not NO...

I've always attached the boot SATA SSD or boot SATA HDD (God forbid!) to Port 0 of the four gray ones in our Z440 and Z640 workstations (they're numbered right to left 0, 1, 2, 3 as shown in the diagram and printed in tiny numerics on the motherboard). Not sure if that truly matters... he'll know.