Concept Help with a SFF semi-passive build

[Goatee]

Hey guys (and gals),

I have a couple of questions I hope you guys can help with. I'm building a semi-passive <6L ultra thin (44mm)) gaming case and I have a couple of things I need some advice on.

1) Controlling a secondary PSU from thin-ITX board.

I have a thin-ITX board. Can I use powering up the motherboard to turn on a secondary power supply (HDPLEX 400W DC-ATX) which will power the GPU?

2) Case mounted screen

I have a small space in the fascia of my case (max size, 102mm x 25.5mm), is anyone aware of a small screen I could use in this space (ideally running off the motherboard LVDS header).

Thanks!

 

[Goatee]

I am nearly finished, just got to figure out where the barrel connector is going.



I also really need to figure out how I can only switch the DC-ATX unit on when the board is drawing power.

 

[chx]

I also really need to figure out how I can only switch the DC-ATX unit on when the board is drawing power.

These boards typically have a plug to power a HDD and then you can just run that to an ADD2PSU? If it's SATA, SATA-Molex adaptes are plentiful.

 

[aquelito]

I am nearly finished, just got to figure out where the barrel connector is going.



I also really need to figure out how I can only switch the DC-ATX unit on when the board is drawing power.

Nice build Akasa Galileo ?

What's your CPU TDP ? I guess 35W ?
Your total consumption should be less 200W under synthetic benches.

What you can do is use a single 240W AC Adapter to power both the motherboard and HDPLEX 400W.

- You plug your AC Adapter into the motherboard DC Barrel.
- You use the 2-pin on-board power connector to ouput 19V to your HDPLEX.
- You use a small mosfet switch, connected to a fan header, to switch your HDPLEX ON/OFF.

This is what I do and it works perfectly (courtesy of @QinX).
This is by far the most compact solution for that kind of builds.

I have a Mosfet switch, one 2-pin cable and 240W brick that I do not use

- Mosfet switch that triggers the PS_ON function of your HDPLEX (here it's a SF450 but same principle) :


- 2-Pin on-board power connector used to output 19V to an HDPLEX

 

[Goatee]

The case is a Galileo TU1, I wanted the Galileo TU2 but I got an amazon misprice on the T1 so I will just have to figure out what to put in the gap. Its a great case, like all the Akasa passive cases.

Build is:

Case: Akasa Galileo TU1
CPU: i7-7700T
MB: GIGABYTE MDQ17AI (PCIE 3.0 x4 and PCIE M.2 SSD support)
GPU: GTX1070 Katana
PSU: HDPLEX 400W DC-ATX
Riser: https://www.aliexpress.com/item/BTM...131.html?spm=a2g0s.9042311.0.0.42444c4dSlLa61
Brick: Dell 330W

RAM and SSD are out of my parts bin and will changed at some point.

You are spot on, power consumption is around 190w maxed out.

I really like this approach, really clean. Thanks @aquelito @QinX

- You plug your AC Adapter into the motherboard DC Barrel.
- You use the 2-pin on-board power connector to ouput 19V to your HDPLEX.
- You use a small mosfet switch, connected to a fan header, to switch your HDPLEX ON/OFF.

I can adjust my current setup to make the 2 pin cable to DC-ATX power connection, but whats the spec on the mosfet? Is there a guide on making it? I assume that just replaces the jumper I am currently using on the PS_ON.

Thats really helpful advice! Thanks again,.

@chx I think I will go with the mosfet but the ADD2PSU looks really interesting, thanks for the pointers.

 

[aquelito]

@QinX described both the Mosfet and Add2PSU solutions a while back in the ultimate thin mini-itx thread :

https://smallformfactor.net/forum/threads/thin-mini-itx-with-discrete-graphics-card.529/#post-14898

PS_ON from your HDPLEX connected to Mosfet drain
12V from fan header connected to connected Mosfet gate
GND from fan header connected to Mosfet source

I'll check the Mosfet reference I am using. I think I have some left in my stuff if you need.

 

[Goatee]

@aquelito that is great!

Did you have a spare mosfet setup you might be willing to part with?

 

[aquelito]

I may be able to send you the one that's already built and posted above
Will let you know quickly if it's available.

 

[Goatee]

I may be able to send you the one that's already built and posted above
Will let you know quickly if it's available.

@aquelito that would be great. Let me know how much you want. I’m UK based