Why not both? The DUAL current steam machine.

[NFC]

NFC, I'm getting a total volume of 0.87L for the Dell 330W from those measurements, correct? I feel like I'm kicking a dead horse here, but external bricks being "too large" was a major concern at the start of this discussion. I want to get that out of the way before I move onto this PSU suggestion. Take a look, please.

The image above is a TFX-350 unit released by Seasonic. It's a hair smaller than SFX. It's comparable in size and shape to that of a laptop brick. It's semi-passive, and it received favourable reviews at SPCR. So, it is very quiet. Power delivery is great, 80+ Gold, and Johnny Guru thinks highly of the unit. This little guy can tame the Nano at price point well below other DC-DC solutions.

Add some custom wires and/or a nice sleeve job and I could see this PSU reliably powering a new design. Anyone have any experience with this unit?

That is awesome looking! I dunno about using it externally (that's your arena) but I have a mod this would be perfect for! Thanks for sharing

 

[iFreilicht]

I understand where this idea is coming from, but I personally would never buy into it. I find external PSUs to be a bit odd already, but the thought of putting an ATX PSU below my desk and running 4 cables comprised of about 40 wires to my "Small" PC, seems completely nonsensical to me.

As you said, this shouldn't be a discussion about power bricks, but I think allowing the use of an ATX compatible PSU externally is something quite different to just laptop bricks and it should be discussed whether that is actually viable.

 

[Runamok81]

I understand where this idea is coming from, but I personally would never buy into it. I find external PSUs to be a bit odd already, but the thought of putting an ATX PSU below my desk and running 4 cables comprised of about 40 wires to my "Small" PC, seems completely nonsensical to me.

As you said, this shouldn't be a discussion about power bricks, but I think allowing the use of an ATX compatible PSU externally is something quite different to just laptop bricks and it should be discussed whether that is actually viable.

Most folks already have more than one wire exiting the PC under their desk. You could sleeve the PSU wires if you wanted to group them into one.

 

[iFreilicht]

Most folks already have more than one wire exiting the PC under their desk. You could sleeve the PSU wires if you wanted to group them into one.

That is true, but you still have to connect all of them separately.
At least all the cables that are connecting devices to a PC now are relatively flexible, which can't be said about a single 40 wire sleeved mess. Right now, there are 12 cables connected to my PC (1 power, 3 displays, 2 audio, 1 network, 5 USB). With a brick, this number stays the same, but with an external ATX PSU, it increases by a factor of 5. If we just count connectors, we still get 5 additional connections.
I think this could make a little bit more sense if you were to design a general enclosure for the PSU that had an internal adapter to something proprietary, much like Project Quantum.
This would also solve the current issue with your design: ATX PSUs aren't designed to be operated outside of a case. The cables are not shielded from EMI, so if you didn't design an enclosure with a custom connector and cable, you'd have to add filter caps inside your case to get voltages within the standardised tolerances to the internal components.

Still, the question remains: Why would anyone want to do that?
If you have limited desk space and therefore use an external brick with a case like the S4 Mini, that brick can just hang from your desk, flapping in the breeze. You can't do that with a big SFX or ATX PSU, those have to sit somewhere.
If you want to mount the PSU below your desk or somewhere out of sight, wouldn't it make more sense to make a VESA mountable case that can just be mounted anywhere and have all the Front I/O (including an ODD, maybe) in a small box on your desk?
If you want a small case for portability reasons, an external ATX-compatible PSU completely defeats the point of the exercise.

 

[Bieberfever]

Kinda getting away from the direction this thread is going in, but in my mind this is a perfect way to "modularize" the Flex ATX power supplies (specifically the 500W FSP) without resleeving, cutting cables or voiding warranties. Anyone this this will/won't work?

 

[Runamok81]

If we just count connectors, we still get 5 additional connections. ATX PSUs aren't designed to be operated outside of a case. The cables are not shielded from EMI. If you have limited desk space and therefore use an external brick with a case like the S4 Mini, that brick can just hang from your desk, flapping in the breeze. You can't do that with a big SFX or ATX PSU, those have to sit somewhere.

I hope you don't mind, but I've narrowed down your post to what I think are valid concerns for most folks.

Additional connectors - Good point. While Molex connectors are sturdier and take more force to connect, they are NOT as convenient as a laptop DC connection. Until someone solves that, then it WILL take more time to connect and disconnect and imagine it would be an inconvenience for folks who frequently travel with their PC. I haven't seen how Quantum solved that. Has anyone seen how their external PSU connected to the PC?

EMI - Having experienced this with PCIe riser cables, I understand that EMI is a real concern for high-frequency signals. But, are the concerns the same for power wires? I'm recalling the Power Mac G4 cube which used an external 205W power supply to good effect. I don't recall any exotic shielding on those cables, and I din't think anything extra was necessary for power wires. Is this a poor assumption?

The dangling - I'm having trouble imagining the physical differences between a unit dangling a Dell 330W brick and the TFX unit I linked to. What am I missing here? The TFX unit has a fan guard. It weighs less and fits into the same space as the Dell brick. What else makes them so different?

 

[SaperPL]

The dangling - I'm having trouble imagining the physical differences between a unit dangling a Dell 330W brick and the TFX unit I linked to. What am I missing here? The TFX unit has a fan guard. It weighs less and fits into the same space as the Dell brick. What else makes them so different?

The cord is hard attached to the laptop brick while you'll most likely use modular TFX - there's a risk of detaching the modular plugs while running - the peg and atx connectors are making the cord less flexible since there's a lot of wires spread on bigger area of plugs.

TFX has sharp edges and can scratch walls and furniture

You have to put the TFX the way it won't block it's inlet and outlet because it has active cooling

Laying on the ground brick will pull a lot of dust quickly

IEC C13-C14 connector is easier to disconnect than C5 connector from the brick because it's intended for stationary use.

 

[Runamok81]

The cord is hard attached to the laptop brick while you'll most likely use modular TFX - there's a risk of detaching the modular plugs while running - the peg and atx connectors are making the cord less flexible since there's a lot of wires spread on bigger area of plugs.

TFX has sharp edges and can scratch walls and furniture

You have to put the TFX the way it won't block it's inlet and outlet because it has active cooling

Laying on the ground brick will pull a lot of dust quickly

IEC C13-C14 connector is easier to disconnect than C5 connector from the brick because it's intended for stationary use.

There is nothing special about this TFX unit that would make it attract more dust than any other PSU. You could of course put an 80mm dust filter on it if you wanted. That may make a nice addition, but it doesn't seem required to me. The edges are sharper,no doubt about it. If it is swinging around the back of your desk, some corner caps, corner guard or gaffers tape may be required to fix that. Both the Dell and TFX unit share the same C13 connector on the AC end. So, there is no increased risk of disconnect on that end. There are indeed differences on the DC side. The Dell is permanently attached and instead, the TFX unit has molex connectors with locking tabs. I suppose the lock tabs could break if they are unable to support the weight of the unit itself. Anyone know for sure? Agreed, the wires will be less flexible.

 

[iFreilicht]

Kinda getting away from the direction this thread is going in, but in my mind this is a perfect way to "modularize" the Flex ATX power supplies (specifically the 500W FSP) without resleeving, cutting cables or voiding warranties. Anyone this this will/won't work?

The only downside I see is that it takes a lot of space.

I hope you don't mind, but I've narrowed down your post to what I think are valid concerns for most folks.

I don't mind you skipping over points, ultimately it's your project and you don't have to justify every decision you make.

Additional connectors - Good point. While Molex connectors are sturdier and take more force to connect, they are NOT as convenient as a laptop DC connection. Until someone solves that, then it WILL take more time to connect and disconnect and imagine it would be an inconvenience for folks who frequently travel with their PC. I haven't seen how Quantum solved that. Has anyone seen how their external PSU connected to the PC?

Like this:

The connector in the left corner is the power connector which carries only 12V. The 3.3V and 5V are generated with a small DC-DC converter board inside the case.

EMI - Having experienced this with PCIe riser cables, I understand that EMI is a real concern for high-frequency signals. But, are the concerns the same for power wires? I'm recalling the Power Mac G4 cube which used an external 205W power supply to good effect. I don't recall any exotic shielding on those cables, and I din't think anything extra was necessary for power wires. Is this a poor assumption?

You don't need fancy shielding or coaxial cables like some PCIe risers use, that's true. And in real world use, you probably won't even experience any repercussions for using just the bare wiring. But as you don't know what environment your case is going to be used in, having a basic shield around the wires is good practise and avoids any unwanted surprises.

The dangling - I'm having trouble imagining the physical differences between a unit dangling a Dell 330W brick and the TFX unit I linked to. What am I missing here? The TFX unit has a fan guard. It weighs less and fits into the same space as the Dell brick. What else makes them so different?

To be fair, I only have used very small bricks in practise, so I don't know about the weight of those high performance models, so you might as well be able to have an external ATX PSU laying wherever.

The cord is hard attached to the laptop brick while you'll most likely use modular TFX - there's a risk of detaching the modular plugs while running - the peg and atx connectors are making the cord less flexible since there's a lot of wires spread on bigger area of plugs.

There's absolutely no risk of that happening. If anything, using all those molex connectors makes the PSU less prone to disconnect. The modular plugs all have locking mechanisms.

TFX has sharp edges and can scratch walls and furniture

You have to put the TFX the way it won't block it's inlet and outlet because it has active cooling

Laying on the ground brick will pull a lot of dust quickly

All good points, didn't think about that.

IEC C13-C14 connector is easier to disconnect than C5 connector from the brick because it's intended for stationary use.

Do you mean it's harder to disconnect? Either way, I wouldn't let that count. Firstly, any of these connectors can be connected in two seconds, even if the exertion force is slightly different. Secondly, as Runamok said, the high power laptop bricks all have to use a C14 connector anyway.

There is nothing special about this TFX unit that would make it attract more dust than any other PSU. You could of course put an 80mm dust filter on it if you wanted. That may make a nice addition, but it doesn't seem required to me.

The point is that it is actively cooled as opposed to the laptop bricks which passively dissipate their heat. That means that a ATX compatible PSU could fail after a time when it's constantly operated on the floor, while that can not happen (at least not due to dust) with a laptop brick.

 

[SaperPL]

There's absolutely no risk of that happening. If anything, using all those molex connectors makes the PSU less prone to disconnect. The modular plugs all have locking mechanisms.

I'm talking about situation where the brick is hanging on those cables and that the whole plugs being quite hard attached to the cord and ain't easily moving around since the wires aren't so flexible it works kind of the same way with what you're trying to do when disconnecting old molex plug. Locking mechanism will most likely fail in time when there's whole TFX hanging on two plastic locks.

Do you mean it's harder to disconnect? Either way, I wouldn't let that count. Firstly, any of these connectors can be connected in two seconds, even if the exertion force is slightly different. Secondly, as Runamok said, the high power laptop bricks all have to use a C14 connector anyway.

What I mean is that there's general use C14 connector that latches only by its pins and there's a clearance between plastic since it would be hard to make a perfect tight fit. Because of that not every C13-C14 connection will need the same force to disconnect. I also think that in those plugs they might be some slightly modified connectors to make a tighter fit.

By the way, there's another thing - you'll have a power switch on some power supplies and you wouldn't want to accidentally touch that too.

 

[iFreilicht]

I'm talking about situation where the brick is hanging on those cables and that the whole plugs being quite hard attached to the cord and ain't easily moving around since the wires aren't so flexible it works kind of the same way with what you're trying to do when disconnecting old molex plug. Locking mechanism will most likely fail in time when there's whole TFX hanging on two plastic locks.



What I mean is that there's general use C14 connector that latches only by its pins and there's a clearance between plastic since it would be hard to make a perfect tight fit. Because of that not every C13-C14 connection will need the same force to disconnect. I also think that in those plugs they might be some slightly modified connectors to make a tighter fit.

By the way, there's another thing - you'll have a power switch on some power supplies and you wouldn't want to accidentally touch that too.

I'll disagree with you on your first point. From my personal experience, those connectors, including the locks, are rock solid. It is true that a completely fixed cable is a better and longer lasting solution, but the locks are the last part I'd worry about breaking when hanging a PSU from those connectors. I guess someone will have to test that.

Of course, there is a bit of tolerance within the exertion force, but I fail to understand how that is a problem with ATX PSUs in contrast to latop bricks.

The power switch on the PSU is both good and bad. On one hand, you can easily turn it off so your PC pulls 0W from the wall. On the other hand, it might get triggered accidentally, as you said. Only time can tell how often that happens, though, and it could easily be fixed with an enclosure for the PSU.

 

[Phuncz]

I'll disagree with you on your first point. From my personal experience, those connectors, including the locks, are rock solid. It is true that a completely fixed cable is a better and longer lasting solution, but the locks are the last part I'd worry about breaking when hanging a PSU from those connectors. I guess someone will have to test that.

I'd be much more worried about the pins and wires failing than the Molex connectors, because of said lock.

But the bundle of wires from an internal PSU are also very rigid, with them bundled up, this basically becomes a 1-2" thick hose of stiff wires. This is just more than a few serious negatives for a few positives.

 

[bhtooefr]

You know, I'm wondering if things would be better if the PSU connector were just condensed to the individual rails. +12V1, +12V2, -12V, +5V, +3V3, +5VSB, and GND. The +12V and GND wires would have to be thicker (I'd say 6 AWG?), but it could work. Looks like there's some high-current D-sub connectors available, too, which would be extremely secure and could anchor into the chassis.

 

[Runamok81]

I'd be much more worried about the pins and wires failing than the Molex connectors, because of said lock.

But the bundle of wires from an internal PSU are also very rigid, with them bundled up, this basically becomes a 1-2" thick hose of stiff wires. This is just more than a few serious negatives for a few positives.

Unless they were unlseeved and unbundled, I don't see how one could frequently snag wires with enough force to dislodge the pins. But I suppose its possible. Sleeve and bundle the wires and that risk is reduced. I agree that the bundled wires will ahve a larger diameter and they will be stiffer and less flexible than the cord from a laptop power brick. No getting around that.

 

[iFreilicht]

You know, I'm wondering if things would be better if the PSU connector were just condensed to the individual rails. +12V1, +12V2, -12V, +5V, +3V3, +5VSB, and GND. The +12V and GND wires would have to be thicker (I'd say 6 AWG?), but it could work. Looks like there's some high-current D-sub connectors available, too, which would be extremely secure and could anchor into the chassis.

I think that would be the way to go. For 12V and GND, you'd just use multiple pins on the D-Sub connector, all wires could have the same gauge. -12V could be omitted completely, IIRC, it is discussed to remove this pin from the ATX12V specification anyway, -5V already was removed a decade or so ago.

You could also go the AMD route and just let the connector carry 12V and generate 3.3V and 5V from that internally, but that would increase the cost of the case significantly.

Unless they were unlseeved and unbundled, I don't see how one could frequently snag wires with enough force to dislodge the pins. But I suppose its possible. Sleeve and bundle the wires and that risk is reduced. I agree that the bundled wires will ahve a larger diameter and they will be stiffer and less flexible than the cord from a laptop power brick. No getting around that.

I don't think the pins would get dislodged, but the wires could break off of a pin. In any case, bundling does indeed decrease this risk.

 

[Runamok81]

I needed to compare ordered a Seasonic 350W TFX.

SPCR and JohnnyGuru both recommend as one of the most quiet and well-built TFX units.

It shows.

Here it is next to the Dell 330W laptop power brick. There are nearly the same size and dimension. TFX is a hair smaller, but taller.

Cable width comparison. The folded back cables are unneeded.

Quick cable flex and strength test comparison video.

https://www.youtube.com/watch?v=vPz0JRnBm3M

Note: You do want to press hard on the 20 and 24-pin connectors to insure they are connected.
Hope this helps!