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Power Supply Alternatives to the IEC C14 inlet

EdZ

Virtual Realist
Original poster
May 11, 2015
1,578
2,107
With common PSUs getting smaller (SFX, FlexATX), more and more of the rear vent area is getting taken up by the IEC C14 inlet, restricting available airflow. On top of this, any case that uses an internal cable to allow more flexible placement of the PSU gets hit with the length of the C-13 plug too! There needs to be enough clear space above the PSU for a right-angle C-13 plug, and you need to keep almost the entire rear area clear to this eight because you do not know where each manufacturer will place the inlet,, and in what orientation.
For an SFX PSU and Ncases 'low profile' (27mm protrusion) right-angle C13 plug, that's over 200cm^3 of essentially wasted volume.

As far as I am aware, there is no existing (and consumer rated) smaller connector that can also carry at least 6A (needed for 600W PSUs for 110V countries). The C5 plug and C6 inlet occupy a slightly smaller area, but the plug is just as 'tall', and the current is limited to 2.5A (275W for 110v countries) Designing one would be great, but probably outside the scope of anyone other than a very large company with very deep pockets.

An alternative would be a captive cord. An entire captive cord would be the most elegant but would need to be terminated differently for each country's different consumer socket standard, and SFF PSUs probably don't have the volume to split SKUs that much. Bare wires for self-wired plugs are a no-no for consumer goods.
So, the alternative is a captive cord ending in an in-line C14 socket. This could either reside:
- Inside the case somewhere - so you have a nice integrated rear-panel mount socket as in existing cases with an internal extension - but need to find a place to hide the connector, and need to standardise on the length of the captive cable to this area can be placed correctly
- Have the captive socket act AS the rear panel socket, which saves on needing to find room for the internal connector but also needs standardisation on captive cord length, and may restrict PSU placement
- Have a sufficiently long cord that the connector lies outside the chassis entirely. This saves space both inside the case AND on the back panel, and avoids the need for a standardised captive cord length (other than 'longer than x'), but means you need a user installable cable grommet (to prevent wear on the captive cable) and has an unsightly and inconvenient lump sitting some distance outside the chassis.
the final drawback of a captive cable is that it is not user-replaceable without voiding the warrant. A sufficiently high quality cable with a wear resistant outer sheath would assuage consumer fears of 'built to fail', but would noticeable increase price over a regular C14 socket.
 
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iFreilicht

FlexATX Authority
Feb 28, 2015
3,243
2,361
freilite.com
what about having the C14 inlet on the same side as the internal connectors? Not ideal for FlexATX, but SFX could benefit from it additionally by having a completely unblocked exhaust side. You work around all the problems you mentioned for the PSU and as you have to reserve space on the internal connector side of the PSU anyway, you'd have enough space there for a C13 connector.
Doesn't change anything about the connector on the back of the case, but then the case designer could always decide what solution works best for them.
 

EdZ

Virtual Realist
Original poster
May 11, 2015
1,578
2,107
That would definitely be beneficial for cases with an internal cable, though at the expense of designs with the 'normal' PSU location exposed at the rear.
 

EdZ

Virtual Realist
Original poster
May 11, 2015
1,578
2,107
That could work. Might be tricky for safety testing, you'd need to reliably isolate the exposed prongs of the unused input when the other was live.
 

iFreilicht

FlexATX Authority
Feb 28, 2015
3,243
2,361
freilite.com
Hm. You could have an AC ON/OFF switch on the unit, you could make it a DPDT switch that switched the two live wires between the internal and external C14. Ground can stay connected on both connectors always. Would waste little additional space and would make sure that you can't touch live contacts.