Need extra 5V on a Dell R730 - homelab

[xi_Slick_ix]

I recently got to upgrade my home server to a second hand Dell R730 - 2 Procs, 192GB RAM - fun for days. I'm debating between Proxmox and XCP-NG for the OS. This is the 8 3.5" bay model, and I have 8 3.5" drives in, connected to the internal SATA controller. I plan to boot off the internal usb 3 from a USB-to-mSata drive. The last part I'm trying to figure out is 4 256GB SSDs connected to a PCIe HBA (VM Storage). ((Samsung SM871 - 5V, .5A))

 

My problem is I'm not sure where to get 5v power from. I planned to let these SSDs hang out in the back of the chassis relatively near the HBA, but there's no sata / molex / 5v power to draw from. Trying to google / search these forums for a way to get 5V from a PCIe slot is quite the rabbit hole. Some routes would have you look at 12v to 5v style buck converters. Another route leads you to devices like this (https://www.amazon.com/Sedna-Express-Adapter-Connector-Included/dp/B01452SP1O). This adapter card clearly converts the 12V from PCIe to 5V, so these devices exist in some manner.

Any thoughts on where to get power?

[Windows7ge]

I have no experience with XCP-NG but I do like PROXMOX a lot. Some things still need to be done via CLI but otherwise the WebUI is very user friendly and feature packed.

 

If you're not afraid of playing with a soldering iron you could tap a 5V rail coming off the PSU. I'm not sure if SATA 2.5" SSDs that use SATA power will run off only the 5V pins or if they need the 12V pins as well. I know they don't need the 3.3V pins but you may need 12V & 5V together. Don't quote me on that though.

 

Alternatively you might be able to find or create a cable that taps off the PCI_e slot power. You'd still need a soldering iron though.

[mariushm]

You can buy molex  to sata adapter cables, here's a couple of examples:

 

1. https://www.newegg.com/black-startech-12-cable-connectors/p/N82E16812400306?Description=molex to sata cable &cm_re=molex_to_sata_cable-_-12-400-306-_-Product

 

 

 

2. https://www.newegg.com/p/N82E16812270493

 

 

 

The red wire is 5v , the yellow wire is 12v. Most SSDs only use 5v, so you could probably not even connect the 12v wire to anything.

You can easily figure out which wire is 5v, it's in the center of the SATA connector. You have 12v on one edge, 5v in the middle, 3.3v (if installed) on the other edge

 

 

So even if all wires are black like in the case of the 2nd adapter cable, you can easily figure out which wire is 5v, which one is 12v and which ones are ground (or COM for common, black wires)

If your server power supply has a molex connector, then you're settled, you just plug the cable in a molex connector and you have 4 sata connectors.

IF you don't, then it's just a matter of finding a 5v and a 12v wire and 2 ground wires and attaching the wires that go in the molex connector to those wires. Preferably you'd solder them, but you could just use a sharp blade to remove a bit of insulation from the psu wires and twist your wires to those psu wires to make a good connection and then use electrical tape to lock everything in place.  I'd recommend soldering as it's safer, or cutting the wires of the psu to make a better mechanical connection (twist the two wires together better or use one of those things with two screws that can connect two wires together... here's an example: https://www.amazon.com/Nextronics-Tool-Free-Wire-Connectors-pieces/dp/B06XWMXZTD/

 

As for power consumption... typically a SSD will consume up to 8-10 watts or so (so up to 5v 2-3A) but only when writing and usually for long bursts of write. When reading or just idling, a SSD will typically use less than 1w

So if a single drive says on it 5v 3A, you don't really need 4 x 3A = 12A for your four SSDs

 

 

 

[32Dave]

If you have a internal usb header you could grab 5 volts from there and ground for that matter not sure about the amperage. My server has 14 hdds 13 sata 1 usb and I made my own cable to custom fit just used a old power cord from an old psu and used the crimp (squeeze) connectors 

[Salacious B Crum]

get yourself some wago connectors and probe for a 5v point and tap in

 

https://www.wago.com/us/c/wire-splicing-connectors

[mariushm]

USB headers are rated at 1A per pin, you may get 2A out of a single usb 3 or usb 2 header but one shouldn't go above 1.5A ... basically same electrical ratings as fan headers as the pins have about the same thickness.

So it would be safe to make a usb 2 / usb 3 to 1 or maximum 2 sata connectors.... I'd recommend maximum 1 sata connector per usb port (2 ports in a header).

However, it's just easier and cheaper and safer to use one of those molex to n x SATA connectors and if you have to, cut the molex connector.

 

[xi_Slick_ix]

I greatly appreciate everyone's input. Finding a 5v source and splicing into that seems to be the recommended method if possible. I honestly am a bit nervous on that front, so here's hoping probing around the board with a voltmeter I can find some 5v pins. 

 

Is there really not an off the shelf component anyone knows of for converting the 12V PCIe to 5V? There would be ample power from that source, and given the fan arrangement on this system very little chance that there would be much heat build up of any kind from the conversion.

[mariushm]

You can buy all kinds of DC-DC converters

 

here's some examples

 

50w : VRAE-10E1A0G Bel Fuse Inc. | Power Supplies - Board Mount | DigiKey

80w : OKY-T/16-D12P-C Murata Power Solutions Inc. | Power Supplies - Board Mount | DigiKey

80w : OKX-T/16-D12N-C Murata Power Solutions Inc. | Power Supplies - Board Mount | DigiKey

 

These are fairly simple to use : you need one or two resistors (or a potentiometer) between two pins to configure the output voltage (the max output voltage of the above is 5.1v and 5.5v respectively) and you need to connect the enable pin (if any) to either the input voltage or ground (depends on version) to turn on the regulator.

That's it. May have to also put capacitor on input and output (something like let's say 100-470uF 16v+ on input and  470-1000uF 6.3v+ on output)

It's all well explained in their datasheets.

 

There's also "power supply" style adapters, which have their own box and all that, here's some examples:

 

25w:

313080006 Seeed Technology Co., Ltd | Power Supplies - External/Internal (Off-Board) | DigiKey

SD-25A-5 MEAN WELL USA Inc. | Power Supplies - External/Internal (Off-Board) | DigiKey

 

50w:

SD-50A-5 MEAN WELL USA Inc. | Power Supplies - External/Internal (Off-Board) | DigiKey

 

90w:

SD-100A-5 MEAN WELL USA Inc. | Power Supplies - External/Internal (Off-Board) | DigiKey

 

 

AC to DC converters (like laptop adapters) :

25w: SDI36-5-U-P5 CUI Inc. | Power Supplies - External/Internal (Off-Board) | DigiKey

30w: GST60A05-P1J MEAN WELL USA Inc. | Power Supplies - External/Internal (Off-Board) | DigiKey

40w: RR9LA8000LCPIM(R6B) GlobTek, Inc. | Power Supplies - External/Internal (Off-Board) | DigiKey

40w: RR9KA8000CCPIM(R6B) GlobTek, Inc. | Power Supplies - External/Internal (Off-Board) | DigiKey

 

Just cut the barrel plug, or use a barrel jack connector.

 

For these last , your drives will be powered 24/7 but you can easily fix that with a 12v relay: connect the 12v relay to the 12v of the power supply. When the power supply powers on and supplies 12v, the relay engages and connects the 5v output of the AC adapter to your chain of connectors.

When and if the psu shuts down, the relay loses power and disconnects the 5v shutting down the ssds.

 

[Salacious B Crum]

13 hours ago, xi_Slick_ix said:

I greatly appreciate everyone's input. Finding a 5v source and splicing into that seems to be the recommended method if possible. I honestly am a bit nervous on that front, so here's hoping probing around the board with a voltmeter I can find some 5v pins. 

 

Is there really not an off the shelf component anyone knows of for converting the 12V PCIe to 5V? There would be ample power from that source, and given the fan arrangement on this system very little chance that there would be much heat build up of any kind from the conversion.

Well this is untested for your application but I just bought these for my holiday lights maybe this will be an option

 

https://www.amazon.com/gp/product/B00J3MHT1E/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

[xi_Slick_ix]

@mariushm @mrbilky

 

Thanks guys, I looked over the motherboard again and realized there are eight pin GPU power connectors on the PCIe riser cards. I do not have plans of putting a GPU in this system, so that should be an easy place to pull 12v and convert to 5. 

 

Picture is not my system, but you get the idea. 

[Salacious B Crum]

Yep that would be ideal post how you make out as many have had similar questions regarding these server upgrades my R710 and R410 don't have these options so I will have to tap inline somewhere when that day comes just haven't had the need yet