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Akitio Thunder2/3 Power Draw Help / Dell DA-2 switching  

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23mrtbone
(@23mrtbone)
Eminent Member
Joined: 5 years ago
 

Just wondering something. Backstory: I am planning to use the Thunder2 with a 1060 card. So the card has a 6-pin and from what I understand that is 75 watts. And I know to get the Dell DA-2 adapter to provide power to the card (which is an 8-pin connector) as well as provide power to the 2.5 x 5.5 mm barrel plug. I am planning to get an 8 pin to dual 6+2 pin. So one 6 pin to the 6 pin required on the GPU and one 6 pin (modded to a barrel) for the enclosure power. 

My question is this. Everywhere I see, people connect a 6-pin to Barrel mod to the barrel plug, so that's essentially a 75 watt exchange, which is fine. Okay, but the PCI-E slot itself can draw 75 watts alone, not counting the (what, 20+ watts?) draw for the thunderbolt port PCB? Does anyone know if providing an 8 pin to Barrel mod (which would be up to 150 watts I believe) be of better performance to provide ALL the power necessary for the thunderbolt PCB and the PCI-E 75watt draw? I know these expansions are rated to "accept" up to 120 watts...so would using an 8 pin to Barrel mod be too much or is it really pushing 150 watts to the barrel or not?

I'm just curious if the 75 watts from the 6 pin to barrel mods are degrading performance any since the thunderbolt and the 75 watt PCI-E slot is sharing wattage's.

 

Thanks!

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Yukikaze
(@yukikaze)
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Joined: 5 years ago
Builds: 24
 

A few things to keep in mind:

1) Note that the 8-pin connector on the Dell DA-2 is not a regular 8-pin plug. The pin arrangement is different, so please take care to wire it correctly.

2) You can easily run 120W of power through a 6-pin connector, so the 6-pin to barrel plug is not an issue. To elaborate: The connector itself is far sturdier than needed for only power delivery simply because it also needs to handle the connection/disconnection stress. As for the wires: A short run of standard 18AWG wires (that is usually what these splitters are built of, in my experience, and it should be marked on the wiring) can also easily handle the 10A of current on three wires, so that is also safe. Note that most Molex to 6-pin adapters, for example, take only two 12v lines to feed the three 12v lines of a 6-pin connector via a 2xMolex to 1x6-pin adapter. These are standard and have been in use for ages, so following that logic you can easily push 75W through only two of your three 12v lines in your 6-pin without any ill effects. Add in a third wire and you can definitely push 50% over that (to be honest, you can also push even more, the cabling for PC components has a lot of safety built in, especially for a cable run of under 1ft like you are going to do here).

3) The Thunderbolt circuitry doesn't eat as much power as you think. The controller itself is rated for only a watt or two. The 120W figure also includes 15W power delivery to an additional chained Thunderbolt device.

4) There is no "degraded performance" - If you don't feed enough power, the card will simple crash your system at some point, or crash its driver.

Want to output 4K@60Hz out of an old system on the cheap? Read here.
Give your Node Pro a second Thunderbolt3 controller for reliable peripherals by re-using a TB3 dock (~50$).

"Always listen to experts. They'll tell you what can't be done, and why. Then do it."- Robert A. Heinlein, "Time Enough for Love."

 
2012 Mac Mini [3rd,4C,Q] + RX 480 @ 10Gbps-TB1 (Atto Thunderlink) + macOS 10.15.7 [build link]  


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23mrtbone
(@23mrtbone)
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Joined: 5 years ago
 
Posted by: Yukikaze

 

A few things to keep in mind:

1) Note that the 8-pin connector on the Dell DA-2 is not a regular 8-pin plug. The pin arrangement is different, so please take care to wire it correctly.

2) You can easily run 120W of power through a 6-pin connector, so the 6-pin to barrel plug is not an issue. To elaborate: The connector itself is far sturdier than needed for only power delivery simply because it also needs to handle the connection/disconnection stress. As for the wires: A short run of standard 18AWG wires (that is usually what these splitters are built of, in my experience, and it should be marked on the wiring) can also easily handle the 10A of current on three wires, so that is also safe. Note that most Molex to 6-pin adapters, for example, take only two 12v lines to feed the three 12v lines of a 6-pin connector via a 2xMolex to 1x6-pin adapter. These are standard and have been in use for ages, so following that logic you can easily push 75W through only two of your three 12v lines in your 6-pin without any ill effects. Add in a third wire and you can definitely push 50% over that (to be honest, you can also push even more, the cabling for PC components has a lot of safety built in, especially for a cable run of under 1ft like you are going to do here).

3) The Thunderbolt circuitry doesn't eat as much power as you think. The controller itself is rated for only a watt or two. The 120W figure also includes 15W power delivery to an additional chained Thunderbolt device.

4) There is no "degraded performance" - If you don't feed enough power, the card will simple crash your system at some point, or crash its driver.

   

Gotcha, that all makes sense. Was just curious, thanks for the response.

I understand the 8 pin from the Dell DA-2 isn't a typical 8 pin, but in your experience, is it safe to say an 8 pin to dual 6+2 pin would be okay to use? I see people use a 6 pin to dual 6 pin y-splitter, but I was hoping to avoid the paper clip on the Dell's 8 Pin ends like I see in the guides. I also have no problem with taking an 8 pin and converting that to a 6 pin and a barrel if I knew which slots in the 8 pin to connect it all to. I have an idea but I would want to be certain. 

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Yukikaze
(@yukikaze)
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Joined: 5 years ago
Builds: 24
 

An 8-pin connector actually has only three 12v lines. The difference from a 6-pin connector is two extra ground wires (you can see that on by the color of the wiring, since 12v is yellow). A splitter to two 6+2 will have the extra grounds also connected. But on the Dell DA-2 these two pins are not grounds, so you'll need to snip that off. In that sense a 6-pin splitter is easier to use because it has no extra wires to get rid of.

If you want a really neat solution, you can do something like this:

Buy a 6-pin splitter and an 8-pin extender. Remove the wiring from the female side of both (it is secured by small metal flaps which can be moved with a small thin screwdriver for example: You can google how to do that if you don't know what I am talking about). Then place the wiring from the 6-pin into the 8-pin connector, matching the three 12v lines on the Dell DA-2, each matched by its own ground line. That will give you exactly the power delivery you need. Then all you need to do is to use the leftover cabling to connect from the sense pin on the Dell DA-2 to one of the ground wires. That will power up the power supply when it is plugged into the wall socket. If you place a switch on that connection, then you get an on/off switch too.

Want to output 4K@60Hz out of an old system on the cheap? Read here.
Give your Node Pro a second Thunderbolt3 controller for reliable peripherals by re-using a TB3 dock (~50$).

"Always listen to experts. They'll tell you what can't be done, and why. Then do it."- Robert A. Heinlein, "Time Enough for Love."

 
2012 Mac Mini [3rd,4C,Q] + RX 480 @ 10Gbps-TB1 (Atto Thunderlink) + macOS 10.15.7 [build link]  


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23mrtbone
(@23mrtbone)
Eminent Member
Joined: 5 years ago
 

@Yukikaze Ahhhh okay, that makes a lot of sense now. So, we are basically mimicking the paperclip idea from this image:  https://imgur.com/MwJTxGm but within the female 8-pin female connector instead of the Dell's 8-pin using the left over cables instead of a paperclip. And heck, this could all happen on the inside the enclosure if I got another 8-pin extender to connect to our custom 8-pin you mentioned and to the dell's 8-pin outside the case?

So, based on the image I attached, in our modded 8-pin we've been talking about, I would have to use one of the left over cables to connect one of the "black" wires of the 6-pin (inside the 8-pin) to the sense-pin, which I assume is the "blue" pin in the image? 

Interesting, thanks for all the feedback!

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Yukikaze
(@yukikaze)
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Joined: 5 years ago
Builds: 24
 

Yup, you seem to have gotten the hang of it. You can see a pic of my old cabling from when I was using the DA-2 for a GTX960. I used a 6-pin splitter and just added another pin to it for the sense pin.

Here is the build:

https://egpu.io/forums/builds/hp-zbook-g15-gtx96020gbps-tb2-akitio-thunder2-windows-8-1-enterprise-64-bit-yukikaze/

If you want, I could find it and then take some more detailed pictures. Note that I used only two 12v lines for the barrel plug. The third one went off to power up some 120mm fans I had in a home-made cooling pad for the laptop.

Want to output 4K@60Hz out of an old system on the cheap? Read here.
Give your Node Pro a second Thunderbolt3 controller for reliable peripherals by re-using a TB3 dock (~50$).

"Always listen to experts. They'll tell you what can't be done, and why. Then do it."- Robert A. Heinlein, "Time Enough for Love."

 
2012 Mac Mini [3rd,4C,Q] + RX 480 @ 10Gbps-TB1 (Atto Thunderlink) + macOS 10.15.7 [build link]  


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23mrtbone
(@23mrtbone)
Eminent Member
Joined: 5 years ago
 

Yeah I saw your picture, very handy stuff. I think your picture shows everything out just well Smile

What power switch is that you use for connecting the sense-pin to the ground? Be cool to have a switch so there is no need to unplug the thing every time...unless the Thunder2 does that automatically when no thunderbolt is connected? 

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vava726
(@vava726)
Estimable Member
Joined: 5 years ago
 

If you want to remove the original barrel you can solder    a  8 pin MiniFit Jr 5566-8SPFG(45586-FG) male connector, you can obtain it from a 24 pins atx male connector.

You can also avoid the use of the switch connecting the sense pin of dell da-2 to a point powered by the active thunderbolt connector (red arrow)  and connecting the remote pin to ground.

akitio remote

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23mrtbone
(@23mrtbone)
Eminent Member
Joined: 5 years ago
 
Posted by: vava726

 

If you want to remove the original barrel you can solder    a  8 pin MiniFit Jr 5566-8SPFG(45586-FG) male connector, you can obtain from a 24 pins atx male connector.

You can also avoid the use of the switch connecting the sense pin of dell da-2 to a point powered by the active thunderbolt connector (red arrow)  and connecting the remote pin to ground.

   

Interesting
Hmm, pardon my ignorance; what/where is the remote pin? Could be something I know already but failed to understand the terminology Kappa 

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Yukikaze
(@yukikaze)
Noble Member Moderator
Joined: 5 years ago
Builds: 24
 

Here is the switch I ordered:

https://www.digikey.com/product-detail/en/cw-industries/GRB066A802BB1/CW100-ND/2349680

 

Want to output 4K@60Hz out of an old system on the cheap? Read here.
Give your Node Pro a second Thunderbolt3 controller for reliable peripherals by re-using a TB3 dock (~50$).

"Always listen to experts. They'll tell you what can't be done, and why. Then do it."- Robert A. Heinlein, "Time Enough for Love."

 
2012 Mac Mini [3rd,4C,Q] + RX 480 @ 10Gbps-TB1 (Atto Thunderlink) + macOS 10.15.7 [build link]  


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