Hardware Insights Forum

As I discussed in a previous thread, I'm not convinced that putting 120mm (or even 135/140mm) fans in the top (or bottom, depending on your POV) of conventional ATX PSUs is necessarily better for cooling than the original arrangement with an 80mm fan at the back (or front). But besides the (easy to explain, but ultimately over-simplistic) popular idea that the bigger fans are "better", there's also the fact that much of the area on the front of a lot of modern PSUs is taken up by the modular output connectors.

This made me think: If a new PSU form factor was designed, what if the output connectors were moved to one of the sides (left or right) of the unit? Given that the internal circuitry is usually arranged with the primary on one side and the secondary on the other, this would seem electrically logical. Meanwhile, this change would free up the area at the front of the unit for air intake. I would then use either 80mm or 92mm fans at the front and/or rear, perhaps with some additional ducts and/or baffles to better direct the airflow. As a further bonus, physical access to the connectors may become easier.

It would seem sensible to me to release such a design change together with a new, streamlined standard for output connectors.
Here's my idea of how that could be implemented:

Main power connector

• +12V would of course be most prominent, with perhaps 2 or 3 "groups" of wires for rails with individual OCP. (Each group having e.g. four +12V/GND pairs for up to 20A per rail, or maybe five or six pairs for up to 25A or 30A per rail? Or if a more stable ground is necessary, maybe use a 3‑row connector with two grounds for each +12V line?)
• Ditch −12V, obviously, as it's pretty much obsolete already (any future‑standard board retaining PCI slots or RS‑232 ports can just generate it with a buck‑boost converter)
• Ditch +3.3V, as hardly anything draws from it other than the RAM (and then only to give sufficient loading for proper operation of older PSUs)
• We can probably do without a main +5V rail on this connector, too, and convert to it on-board for the stuff that needs it.
• Possibly replace +5VSB with a +12VSB?
• Maybe add some higher voltage, such as +20 or +24V, alongside the existing +12V? (If it can be adequately justified…)

Supplementary +12V connectors
Would probably not be greatly different from the existing 4‑ and 8‑pin ATX12V/EPS12V. (On that note, I'm not sure why they didn't just reuse those arrangements for PCIe power, rather than creating something seemingly different-just-for-the-sake-of-it…)

Low-current connectors for peripherals
If we don't keep the old (and somewhat poorly designed) large 4‑pin +12V/+5V connectors, I'd personally follow the KISS principle and go with a simple 2‑pin connector, with one +12V and one ground wire.

Power for storage devices (SATA, SAS etc.)
I'd provide this via the mainboard (or RAID adapter or similar associated device), rather than directly out of the PSU.

It could be debated whether to have a single large main connector (rated to power most or all of a system), or to provide individual cables for each heavier load (CPU, GPU, etc.); the former is physically neater, but the latter may make more sense electrically. As something closer to the "best of both worlds", I wouldn't mind having a few heavy-gauge wires (perhaps shielded if necessary to suppress crosstalk with nearby traces) – or perhaps busbars – strategically run between points on the mainboard; with adequate reinforcement at the terminations, to ensure that they don't break off too easily.

One more thing: If we want gold plating, then it should be a mandatory part of the new standard – to ensure that both sides will be gold, providing the best‑quality connections and preventing galvanic corrosion.

So, what do you think of this idea? I'd fully expect adoption of such a standard to remain slow, given how long big top PSU fans have been the fashion and not having a truly desperate need for the change, but from a purely technical standpoint?

I think the largest problem is that "new form factor" Just look at how other factors are doing. Yeah, SFX is getting some popularity lately, but even the TFX is still in grave with one leg. BTX and other exotic factors can only work with largest integrators who usually can afford that in the quantity of systems they produce. And believe me, I meet way too many of these each weak when recycling old systems.

Other than that, the problem of single 80/92 fan is that it only cools things in the airstream, which only covers about 60 % of the unit. Maybe two 70mm fans sitting next to each other may be an option. Or two 80/92, one on the front, other in back and in different positions (one left, other right).

You're quite right on inertia, although it doesn't help TFX's case that it's a particularly awkward shape to cool adequately (given the constraints of the PSU internal layout). At least SFX is still a decent design for its small size (with the possible exception of the smallest version, with a 40mm fan - which you'd have to be really desperate about saving space, in order to adequately justify choosing it).

SFX-L seems to have some potential. TFX can actually work as single long tunnel, with the fan either pulling, or pushing the air through. Such configuration is very common in different types of server units, compared to which TFX is taller so it can accomodate larger fan. For example 1U server units only have 40mm fans, and you can imagine what turbine that is