Pro Tower Plus QBT1250, adding a SATA drive, #1

Hi

The pin-outs are not consistent across the range, and I can only post what I have found, which may very well not apply in your case.

When adding or replacing a SATA drive in a Dell Optiplex that uses a proprietary mini 6-pin motherboard connector to standard 15-pin SATA power, understanding the pinout is crucial for safe and reliable operation. Dell’s mini 6-pin connectors are not standard ATX and may vary between models, so always confirm compatibility before making or using adapters.

To begin with does this correspond...

Standard 15-pin SATA Power Connector Pinout

@anne_droid​ Thanks for your help.  I just captured the picture of the power cable from the web and hoped that one could explain how to remap the pins more easily.  I actually brought a black cable like this:

Anyway, I wonder if you could show me how to map the 15 pins with the 6 pins correctly by filling in the last column, assuming a 2 by 3 orientation with the first pin as Pin 1, i.e. the one that is not used.

Thanks again!

Hi

Well I wanted to start at the other end, IE the sata connector of the SSD, and ID the actual SSD so that I felt a little more confident in my search.

ALSO which connector(s) on the main board are you using.

The pinout of a SATA III SSD includes both data and power connectors. For the data connector, there are seven pins, which include three ground pins and four active data lines in two differential pairs for transmitting and receiving data.
 The specific pinout for the data connector is as follows:

Pin 1: Ground (GND)
Pin 2: Transmit+ (A+)
Pin 3: Transmit- (A-)
Pin 4: Ground (GND)
Pin 5: Receive- (B-)
Pin 6: Receive+ (B+)
Pin 7: Ground (GND) 
For the power connector, there are 15 pins, which provide power to the SSD. The power connector includes three voltages: 3.3 V, 5 V, and 12 V, each supplied through three pins.
 The exact pinout for the power connector is not detailed in the provided context, but it is known that the 15-pin power connector is used to supply power to internal SATA hardware such as hard drives and SSDs.

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So the data lines are covered, and you plug a 15 pin power connector into the SSD, and the 5/6 pin onto ????? socket on the main board?

Is that correct so far?

have you any way to test the cables that come from the PSU for their voltage levels?

@anne_droid​  No, I don’t know how to test the voltage levels of the power cables that come from the PSU.

I connected the data cable and the power cable from the SSD to SATA-0 to SATA PWR on the motherboard.

They should be Slot 16 and Slot 12 as shown in the user manual.

The SSD (Samsung 850 EVO SATA SSD) and the data line should be fine since I just reuse them from my old PC.  I bought 2 power cables.  So, the chance of having a defective power cable should be low.  However, since the power cable is designed for Dell Inspiron series only, I suspect that it has to be "re-wired" but I don’t know how to remap the 15 pins to 6 pins.

Hi

Well I can think of 3 lines of approach....

Determine the pin-outs that the cable was intended for (Inspiron MB)

Determine what your MB wants or outputs, hence the voltage test.

Then adjust accordingly.

OR

Determine what the SSD wants and splice into a cable coming from the actual PSU, colour for colour.

DELL do not seem to have published the pin-outs, so it is a tricky one.

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A crude method may be to plug in the 6 pin, after connecting a 12v car bulb (low wattage) to the 15 pin connector, and when it connected to GND and +12v it is full brightness, and GND and +5v it is half of that.  To see if the MB is giving out any correct voltages.  BUT that is hit and miss.

Does any of this make sense.

• Pin 1: Ground (Black)

• Pin 2: +5V (Red)

• Pin 3: +12V (Yellow)

• Pin 4: Ground (Black)

• Pin 5: +3.3V (Orange)

• Pin 6: Ground (Black)

Note: The 3.3V line (Pin 5) is often unused in modern SATA drives, but Dell includes it for compatibility. Always verify with a multimeter before making custom cables or modifications.

SATA Power Cable Part Numbers

• The official Dell part number for the hard drive/optical drive power cable is 5GBWK. This cable is designed to connect the 6-pin SATA_PWR header on the motherboard to standard 15-pin SATA power connectors for drive.

• Some users have reported confusion with similar part numbers (e.g., 5GPWK), so confirm with Dell support or your system documentation before ordering.

Unfortunately I am at the end of my remote support capabilities.

I do not want to give any false hope or incorrect info, resulting in a damaged system.

So without chapter and verse on all of this (like the part number of what you bought etc) I dare not offer anything else.

Sorry.

@anne_droid​ Sadly that there is no documentation from Dell but thanks anyway for your help.  I guess I may need to try the crude method you suggested.  May I know where you got the pintout map?

Well since I'm a bit a of a thicko, so I use perplexity.ai because it lists the places it references for the info it supplies.

Sometimes just a search using duckduckgo search engine to supplement the perplexity info.

This for instance does not match your cable colour code.

https://www.perplexity.ai/search/buy-a-main-board-for-dell-qbt1-qvVLf6m3QcyFqHgQFijHfg

These intrigue me

Because the first part looks like it sidesteps the MB, and would splice into the PSU wiring direct.

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I also looked here ... https://www.dell.com/community/en/conversations/optiplex-desktops/dell-proprietary-6-and-8-pin-sata-power-cable-dpn/647fa297f4ccf8a8de8271ac

https://www.dell.com/community/en/conversations/optiplex-desktops/what-is-the-use-for-the-6-pin-proprietary-psu-connector/647f968df4ccf8a8de95a7ec

The upshot of what I learned, is that I know less than nothing about pin-outs of 6 pin DELL connectors.  But the artwork on your main board may state the purpose of the six pin connector.

@anne_droid​ It seems that the last link is a community accepted solution.  I'll try it.  I just don't understand why Dell doesn't provide the cables and drive bay in the machine.

Thanks.

https://www.dell.com/community/en/conversations/optiplex-desktops/what-is-the-use-for-the-6-pin-proprietary-psu-connector/647f968df4ccf8a8de95a7ec?commentId=647f9693f4ccf8a8de961f51

https://www.dell.com/community/en/conversations/optiplex-desktops/what-is-the-use-for-the-6-pin-proprietary-psu-connector/647f968df4ccf8a8de95a7ec?commentId=647f9693f4ccf8a8de961f51

https://www.dell.com/community/en/conversations/optiplex-desktops/what-is-the-use-for-the-6-pin-proprietary-psu-connector/647f968df4ccf8a8de95a7ec?commentId=647f9693f4ccf8a8de961f51

Hi

This may not be welcome news.....

The Dell Pro Tower Plus Model QBT1250 is primarily configured with NVMe M.2 SSD storage and does not come with a standard SATA drive bay or the necessary SATA power and data cables pre-installed for adding a traditional SATA hard drive or SSD. This means the chassis does not include a dedicated hard drive caddy or bracket for 2.5" or 3.5" SATA drives by default, nor the cables needed to connect such drives.

Hard Drive Caddy / Drive Bay:

• The physical mounting structure for a SATA drive (sometimes called a "drive bay" or "caddy") is not included with the QBT1250 model if it is configured with NVMe storage only.

• Older Dell desktops used blue plastic trays as drive caddies, but the QBT1250 does not appear to include such trays or a dedicated bracket for SATA drives.

• Some users suggest that the metal structure inside the case might allow direct mounting of a 3.5" or 2.5" drive with an adapter, but this is not officially documented.

• Dell does sell a generic hard drive bracket for mounting 2.5" drives in their mid-tower cases, but it is not specified if this bracket is compatible or included with the QBT1250.

SATA Power and Data Cables:

• The QBT1250 motherboard includes one SATA 3.0 HDD slot, but the system lacks SATA power and data cables for connecting an additional SATA drive out of the box.

• Users have reported that the SATA power connector on this model is a proprietary mini 6-pin connector, not a standard SATA power plug, requiring a special adapter cable (Dell part number 5GBWK) to convert it to a standard 15-pin SATA power connector.

• There are compatibility issues with the power cable pinout, and some users have had to swap pins on the 6-pin connector to get the drive powered correctly.

• Because of these proprietary connectors and lack of included cables, adding a SATA drive requires purchasing or fabricating the correct power adapter cable and a SATA data cable.

Summary:

• The Dell Pro Tower Plus QBT1250 does not come with a hard drive caddy or SATA cables for additional SATA drives if configured with NVMe storage only.

• You will likely need to source a compatible 2.5" or 3.5" drive bracket/caddy separately (Dell offers generic brackets but check compatibility).

• You must also obtain a special SATA power adapter cable (Dell part number 5GBWK) to connect the proprietary 6-pin motherboard power connector to a standard SATA power plug.

• A standard SATA data cable will also be needed.

• Installation may require some technical knowledge due to proprietary connectors and potential pin swapping on the power cable.

If you want to add a SATA drive, your best approach is to:

1. Purchase a Dell hard drive bracket for 2.5" or 3.5" drives (confirm compatibility with QBT1250).

2. Obtain the Dell SATA power adapter cable (part number 5GBWK).

3. Use a standard SATA data cable.

4. Be prepared for possible pin swapping on the power adapter cable to ensure proper power delivery.

This approach aligns with user experiences and Dell documentation for this model.

The Dell Pro Tower Plus QBT1250 allows adding an extra SATA drive, but has limited internal bays (one 3.5" bay and one 5.25" bay). You’ll need a free SATA data port and a special adapter for its proprietary mini 6-pin SATA power connector. After installing and connecting the drive, check BIOS to ensure it’s recognized. For best results, consult the Dell manual or a technician.

Just adding a data point here.

We recently purchased a number of QCS1250 Slim & QCT1250 Tower workstations from the new Dell range to replace some ageing machines. Like many we configured with NVMe storage only, with the plan to add additional storage afterwards.

And, like many, discovered that there is no drive caddy in these machines, although it can be added according to the product manuals:

QCS1250: https://www.dell.com/support/manuals/en-au/dell-pro-qcs1250-slim-desktop/dell-pro-slim-qcs1250_om/

QCT1250: https://www.dell.com/support/manuals/en-au/dell-pro-qct1250-desktop/dell-pro-tower-qct1250-owners-manual/

Chasing down with Tech Support, the Dell Part Number is common for both QCS1250 & QCT1250. The drive caddy part number is:

G0WKG - ASSY,BRKT,BAY,HD/ODD,MT/SF,D14

Currently our Sales rep is telling me that we cannot get the HDD bays in a unit that was purchased without additional Dell 3.5" or 2.5" drives, But I'm hoping to overcome this and get empty bays. I will update once I know the final result.

I finally found a solution.  First of all, here is the pinout of the SATA power slot.

So, you need to make sure that the 6-pin end of the SATA power cable follows the same pinout when it plugs into the slot. You can just buy a 15-pin to mini 6-pin SATA power cable and pull out the cables from the 6-pin end and then plug them into the correct slots as shown below.

For the drive caddy issue, I found that a PCI HDD mounting bracket works in my case. I added a GPU card support to make sure that the HDD does not sag.

@SimonKW, your pinout is confusing.  I assume your frame of reference on the motherboard is looking at the pins from above.  For the cable, you show a view of the end of the cable with the corresponding pinout from that view.  If you were to mate that cable with the motherboard, the pinout would not match.