Advice ~~HDPLEX 400W DC-ATX~~ J-Hack users: How is it running for you?

[dc443]

I have my Velka 7 build completed (will post and link from here to the build description and pics for that in the coming weeks! 5800X3D & 3080Ti FE) and I'm looking to plan out a silly alternative power delivery configuration for it for road trips/off-grid capability. To be honest, I think the main driving factor here (not unlike the build itself also!) is mainly just because I can or because it's possible. I think I will find some kind of almost perverse satisfaction to enable the capability of running the PC off DC power direct from battery cells, instead of a likely more practical approach of just using the PSU that it's already got and using a beefy high-quality inverter.

I'm going to be experimenting with and building a DIY power station, so the idea is to have an alternate configuration that I can set up to bypass the internal Corsair SF750.

I already have a really awesome customization capability with this case by being able to mount Noctua fans on the GPU side left side panel which does wonders to reduce noise and temps when pushing the GPU hard. I can do a similar thing on the CPU right side panel to similarly piggyback-mount a DC-ATX unit and use some strategically placed holes (or use existing holes) for routing this alternate ATX power source. This way I can swap between powering the machine via standard 120VAC with its internal SFX PSU and this DC setup by rewiring internal power connectors and swapping the side panel, instead of swapping the internal PSU (which is not practical to do with any regularity given the awesome tightness of the case).

Originally I was going to design my power station to provide ~50VDC (13 or 14S), which would work well with the HDPLEX 800W DC-ATX, but I realized the absurdity of spending $350 on one of those as well as the unlikely prospect of needing or even wanting full power out of the system when in "off-grid" mode. Nor would full power (even 400W max power limit on GPU) ever remotely approach 800W. It being a full fat GA102, might approach that transiently, however...

Anyway, since I shall be completely happy to limit the rig to 400W power draw then, as I think under either Windows or Linux I'll be able to lower the nvidia power limit to, say, 250W, from its default of 350W, I am considering changing the power station battery configuration to 7s (where max voltage at 4.2V is 29.4, still under the 30V max of the 400W DC-ATX). Spending only around $100 on the DC-ATX unit is far more reasonable, I figure. Something I want the ability of this power station to support is 1.5kW burst output, which would work out to 50A, so the wire gauge required remains in an acceptable range (i would need only 30A if this was 50V).

It looks like my plan is shaping up pretty well here, I just want to know if anyone here is getting any heavy use out of their HDPLEX 400W DC-ATX unit. I will definitely need to push it nearly to its limits if I go this route for my build, and it's kind of my baby now so I want to get ahead of any potential pitfalls with the design of this build. I would be particularly interested to see any reviews where they push the unit beyond its rated limits to see how it fares. I wonder if I can get even more out of it with active cooling? I see the review for the unit on this site where the DC-ATX reached only 15C above ambient with a 300W load, which being a passive PSU indicates it is living up to its efficiency rating and likely has potential for headroom. But I'm struggling to find any information about pushing it to 400W and beyond, as well as oscilloscope measurements of voltage stability/ripple and so on. I might have the equipment to do this but probably can't spare the time to actually learn how to do this kind of in-depth testing myself.


Slight sidetopic:
My hope is that in a few years we will get DC12VO as a real possibility in SFFPC and there should be some nice reduction in the number of power supply wires. But this seems not to be possible right now. I would be open to any PicoPSU style solution for this build as it would reduce power wire volume greatly, but since the spec of the system is pretty firm and has a 400W minimum (Can't hold back the GPU *too* much), I don't think there actually exist any trustworthy viable pico PSU that can push this kind of wattage. There is stuff like RGEEK 450W PicoPSU. I do run an RGEEK 250W PicoPSU powering a 5600G build in an RGEEK L80 case (also planning to use a Meanwell EPP-200-12 in there) so at least these things seem to work but (1) Really question if 450W load is gonna be sustainable there, but more importantly (2) 450W worth of DC 30 or 50V -> 12V conversion is still required. That said, though, it looks like there is a pretty extensive market for DC pico-PSUs so maybe there is something viable that I haven't found yet.

Anyway, that is why I think my best bet I've found so far is to just deal with routing all the ATX wires through the side panel and go with the HDPLEX 400W DC-ATX. It's 5 years old, which I hope just means that it's a design that has held up well over that time.

I guess I thought of another concept, which could be to run the thing in this DC configuration 24/7 with the HDPLEX 800W unit internal. Got to evaluate if it can fit inside the case when the SFX PSU is removed. I think it can, but this messes a bit with the GPU flow through area. This would allow for full power utilization and effectively work as some kind of extremely generously specced UPS setup for this rig. I think the problem with this is that its likely not to be practical, and the PSU cutout area would be pretty ugly. I'd be locking myself at that point to requiring something like two of those 330W power bricks to use it in non-UPS mode, and the 800W unit being $350 and the bricks are $90 each, that's over $500, I think I am scratching this concept and the SFX PSU is staying inside the case.

 

[msystems]

It will probably be fine with slight tuning, but you could just use two of them if you find that a single one is tripping OCP, and it's still cheaper than getting the 800w one.

Alternatively you could use an industrial regulated 12v dc-dc buck/boost to just get the 12v. This approach is useful because it's valuable having regulated 12v anyway for any other 12v electronics that the bank could potentially power. You'd need to get one anyway if you are planning to use the bank to run 12v devices.

Then for your PC, if you run non-atx 12v, you'll need to use a Pico style dc-atx psu which just pass the 12v thru but create the other voltages. Like JHack m2426 which is designed to take your regulated 12v and step it down for the 5v and 3.3v needed by the 24 pin connector.

The next version of the DC-ATX will be wide input 12-50vdc, available sometime next year (this is unofficial info). Maybe consider waiting or upgrading to this.
I am using 14v Lithium so I chose to step up to 19v to be able to use the HDplex. But when the next generation dc-atx comes out I will get rid of the step-up.

If you move your rig to a pure DC system i'd suggest looking into ditching the AC-DC atx psu entirely and getting some of the new GAN bricks which will feed your DC-atx when it runs on mains. Then you can downsize the rig. These top out at about 330w currently so you would actually be down-tuning your rig when on mains compared to when on DC.

330W DC+USB-C Adapter Charger

USB C Charger SlimQ Fast Charger USB C Cables Fast Cables GaN Charger Gaming Laptop Charger Wall Charger 100W Charger 230W Charger 180W Charger Legion Charger Alienware Charger Oman Charger

slimq.life

 

[Brian McGuigan]

I understand from HDPLEX, themselves, that the HDPLEX 400W is now obsolete. I was considering using one in a build myself. I am now thinking of using two HDPLEX 250W GaN Passive AIO ATX Power Supplies instead. These are 94% efficient, totally fanless, silent and occupy less space than the HDPLEX 400W and its associated AC-DC converter - and deliver 100W more power. You can even use three or more to deliver 750W, 1000W and so on.

 

[dc443]

Dang you're right, and two of these 400W DC-ATX wouldn't be appreciably bigger than the 800W unit and can be more flexibly positioned. Definitely would be a bit overkill though. Probably I would make the portable mode of this rig be 400W.

Yeah you are right that I do need some sort of 12V supply anyway to provide power for 12V devices, because economies of scale already dictate that any USB-C PD and such doodads I'm going to hook up will be in 12V (up to 16V) automotive format. Yes, thank you for the ideas here. A sufficiently stable 12VDC rail to run a J-Hack on seems to be the ticket here, will look into that. This has many benefits, I can put the high voltage system at any voltage suitable for battery topology and wire gauge, 12V car adapters could run off of it, devices like my 12VDC fridge will be warning me about low battery, these things should still run nominally though. On the PC side, the J-Hack approach comes out way ahead, considering I would definitely need separate battery voltage to 12VDC buck with the HDplex.

A compact GaN AC-DC is definitely attractive, though I have doubts about it being affordable. $150 isn't bad though for what you're getting. Wow that one is really tiny. That's pretty impressive... There would still need to be a 20V -> 12V conversion to run the J-Hack PC off it though... Let me think... Yeah the 50/30/20V -> 12V buck can't practically live inside the PC enclosure since it's needed to run 12V devices when the computer isn't in the picture. Now it is tempting to get one of these adapters just to be able to marvel at the engineering (what is that, like 4x the power density compared to that 140W Apple brick...) but I'm afraid I probably have no legitimate use for such a gadget and already have many sub-100W small 19V bricks around the house and don't need more.

Could you comment on what sort of wattage the upcoming DC-ATX will be? This is interesting since one way to interpret what you said is that this unit might be able to accept exactly 12VDC and not drop it at all for ATX 12V, that would be really impressive, and although there's some questions around how to use this to run other 12V devices off it without requiring the PC to be switched on (again the PC needs to be separable from the bulky power station) this does have potential for drastic system integration, though that gets much muddier if I'm aiming for modularity between the PC and the power station.

Update: I'm impressed by the price points of DC-DC buck units, this helps since it now looks practical to build in extras of these where necessary, so one can exist inside the PC enclosure and another on the power station... Also, they could be set differently, e.g. at 14.5V on the power station and probably a different unit in the PC that guarantees 12VDC. The approach would be to build it out right now with the PC side running a dedicated DC buck (say, 800 watt, for no compromises) into J-Hack, and then upgrade this into a single device in the upcoming HDplex DC-ATX if its wattage turns out to be appropriate. I hope it could be shaped like the recently released 250W GaN AC-DC but much thinner or shorter. Shorter would be so perfect since it can fit where the SFX PSU is right now. If it is 250W or 300W that could be nearly ideal, running two could deliver decent performance. This depends though, since if I can find some overspec'd high quality buck, pairing it with a J-Hack already would be optimal, GaN or otherwise... It's not really like I'll need to sweat 2% of efficiency if it could work like that already as there'll be plenty of airflow in the vicinity. I think it's reasonable to expect that an overspec DC-DC buck could be had in a smaller form factor than SFX.

Edit again: DC-DC 12V buck in GaN form seems possible. A lot of research ahead.

More edit: Seems like DC-DC GaN buck have not quite hit economies of scale. Well let's see... I've got a CUI VFB600-D48-S12 (or D24 for lower input voltage) available to purchase at around $300. It's a lot more compact than I need. Given that incredible half inch thickness, I'll have to assume this is GaN tech. 92% efficiency there is questionable though. Thing sure is sexy though. Continuing to search for more blocky and less expensive options.

Another edit: Haha going through Mouser/Digikey catalogs with filters. This is pretty entertaining

 

[msystems]

I forgot to mention the issue with making the build dependent on external 12vdc is that there currently aren't any good 12v bricks (besides G-unique) so you'd have a problem when trying to use your build on the mains. The gan trend will be for 20v and 48v. So 19v + hdplex is still better at the moment for a hybrid build. Plus making custom wiring from non atx 12v sources is a pain.

Once the hdplex 400w is revised to 12-50v then you can still use it with gan bricks on mains, and on your dc system can be 12v or 24v or anything else without stepping up or down.

 

[msystems]

I understand from HDPLEX, themselves, that the HDPLEX 400W is now obsolete. I was considering using one in a build myself. I am now thinking of using two HDPLEX 250W GaN Passive AIO ATX Power Supplies instead. These are 94% efficient, totally fanless, silent and occupy less space than the HDPLEX 400W and its associated AC-DC converter - and deliver 100W more power. You can even use three or more to deliver 750W, 1000W and so on.

We are referring to the dc-atx module which was not discontinued and is still the market leader for DC systems.

Yes Hdplex's ac-dc is discontinued (replaced by their new GAN module)

 

[dc443]

I forgot to mention the issue with making the build dependent on external 12vdc is that there currently aren't any good 12v bricks (besides G-unique) so you'd have a problem when trying to use your build on the mains. The gan trend will be for 20v and 48v. So 19v + hdplex is still better at the moment for a hybrid build. Plus making custom wiring from non atx 12v sources is a pain.

Once the hdplex 400w is revised to 12-50v then you can still use it with gan bricks on mains, and on your dc system can be 12v or 24v or anything else without stepping up or down.

Thanks. Yeah I am aware of the fact that 12V is a bit restricting, through the APU build I have in which I'm luckily able to fit the Meanwell EPP-200-12 internally to make that system brickless. Since the RGEEK 250W 12V PicoPSU I am using inside came with a barrel plug, I mount the plug to the case, but... it's not going to be very useful and I will need to put a very loud warning that it is a 12VDC only jack requiring regulation. Actually. this project is very unfinished since I have to figure out where to open a hole for the 120VAC to connect the Meanwell.

Another thing I consider is that once I set up the J-Hack it would also improve the PSU cable situation with respect to being rid of the 24-pin (it's not too bad as i've got it custom lengthed, but it definitely pushes the available routing room, any reduction in power wires is a win here). That's another side benefit. So the only drawback of J-Hack approach is that DC input becomes of the inflexible 12V kind, incompatible with bricks generally. It helps to consider it this way in order to weigh the alternatives here.

In preparation for my road trip this week, I just went to undo the front & left side panel in order to swap the mellanox card next to the GPU out for an NVMe card. (There is no way to make my fiber optic cable jack into the mellanox card, so it has to be partly disassembled like this to transition this rig between portable and htpc modes)

It is not too troublesome, but can take up to half an hour. A PSU configuration swap requiring disassembly of the panels would not be attractive. This leads me to the next conundrum:

If I leave the Corsair SFX PSU 12V connection connected to the J-Hack, but power the J-Hack from external 12VDC, then as long as this does not damage or start up the SFX PSU somehow, then actually all I need is to add a 12VDC input in the back of the case and I'd be off to the races. Since this involves no DC-ATX shenanigans courtesy of the extreme compactness of the J-Hack it's definitely the leading choice right now.

Even if it turns out that i somehow HAVE to disconnect the SFX PSU (where it is insufficient even to switch its mains power switch off) from the J-Hack whenever I am powering the J-Hack with 12VDC, I could at least contrive some sort of flip switch making it possible to toggle the connection on the exterior of the case.

Very enticing... I'll have to order one of these j-hacks.

 

[dc443]

J-Hack M2426 limits daisy-chain CPU power to 75W and only uses 4 pin. Since I'm dealing with a 5800X3D this is problematic. I'm close to being ok but it does seem problematic. I suppose I could set PPT to 65W (effectively Eco mode), but it's very much not ideal if I'm wanting a fixed setup for portable and home use where i would like to push it if i can.

the CPU (and GPU) 12V could perhaps be coming straight from the 12VDC coming in, but I think I'll have to sort through switching control with that. But that might be the PS_ON signal from the M2426. Potentially as simple as connecting that to some relays...

 

[msystems]

You'll want to use a load switch to connect the gpu pcie if you want it to gracefully power on and off with the 12v psu. I don't know if the load switch is still available, it was a G unique product

 

[dc443]

Thanks, is a load switch basically a relay but just more optimized (a mosfet instead of a clunky clicker thing)?

 

[dc443]

@msystems how does something like https://www.mouser.com/datasheet/2/632/DS_Q48SC12050-611323.pdf look as a compact industrial grade 12VDC supply? I see its ripple is within ATX spec. But I do not know of other pitfalls to look for.

And I am checking if @REVOCCASES has any more load switches on hand I can get.

I already was able to order more side panels from Michael for my Velka 7 to do the mount mods for this DC-DC equipment. If this 48-12VDC supply can work, it's small enough to go internally in the case, and i'll be tempted to design some sort of lithium based modular UPS unit that can plug into the velka 7 somehow.

 

[msystems]

Depending on what the battery pack is supposed to be powering other than the computer, I would probably just make a 24v bank and still use the 16-30v HDplex just for the convenience (since you get (1)the atx power state functionality and (2)saves time on wiring and (3) compatible with 19v laptop brick). 24v being the second most common voltage, there is a good amount of 24v appliances and stuff designed for 24v which you can use natively, and a 24v to 12v stepdowns are extremely common and fairly priced. 24v to 120vac Inverters are common also.

Because if your plan is to put your dc-dc inside your case, then that doesn't really help you for when you want to power other stuff from the bank. So your bank is going to need it's own 12v step down anyway. So you might as well go 24v.

 

[dc443]

Yeah. I definitely follow you there. However the plans are not contrained like this. I am merely exploring options.

I need to have all of the pieces in front of me so I can move them around and play with them, so to speak.

You see, if I want to keep the SF750 PSU installed inside the PC case, a full ATX complement of cables to deal with and physically replug when switching between DC power and AC power is not going to be nice. So that is really a problem.

This is why I am starting to lean toward some kind of design where I have cables that are all connected up internally and I EITHER plug 12VDC (50A+ capable, regulated), or alternatively 16~30VDC, into it OR I plug the C14 120VAC into the SF750. I'd ilke to be able to switch like this without disassembling the case which requires undoing screws.

So yeah i think at this point this is a bigger thing to figure out (whether its possible to double wire up the power delivery to both psus in a way preventing either side from frying the other) first, and then i can decide later how i want to deal with high voltage dc conversion to 12v. Either that's a picopsu or hdplex dc-atx style. whether it fits all internally or requires some stuff sticking out a little bit, isnt a big deal compared to being able to easily swap modes!

 

[msystems]

Im kind of interested if that's technically possible, but that sounds like a huge pain. I would ditch the SF750 and get two HDplex and a brick for mains. I'm pretty sure you can trigger the second HDplex to turn on by daisy chaining the PS_ON wire. Their inputs can be wired in parallel to an XT-90 E-M connector. I use these on my build and they are great since they are easy to solder to and handle 30-60 amps. Then you build your power pack's output to an "antispark" XT-90 which has a built in resistor for pre-charging, so it's still safe to plug it in to the PC when the circuit is hot without necessitating a separate switch (definitely fuse it though).

On mains you can either butcher the end of a power brick to XT-90, but its not much more trouble to make a short "barrel to XT-90 adapter" without butchering the brick.

 

[dc443]

Yea but that has all the good properties except for one thing which is the pc then has no more brickless capability which would be very silly for the 90% travel portability use case!

The off grid use case is the 10%. And considering that portable all together is like 20%, I'm basically exploring this for a 2% use case. But oh boy would it be awesome.
I might want to reconsider just using a beefy inverter and deferring a design like this for a future build.