250W PSU board?

Hey [H]Fers,

I saw this board on eBay whilst doing my routinely ITX searches and it got me intrigued. However, when I look at the spec sheet it lists only 10A average on the 12V rail with a maximum peak of 13A. From what I know about voltages, shouldn't this PSU board basically be rated more like a 150W board rather than a 250W board?

I've checked with Xilence's 250W SFX PSU and theirs has 18A on their 12V rail so I'm really confused. It would be really interesting if the board that I found on eBay was really 250W though as my i3 2100 + 7850 pulls 170W on max CPU+GPU load from the wall and I'm trying to design a small PC revolving around those two as the main components.

Thoughts?

EDIT: Found the supplier and the specs there are the same.

On the E-Bay item link it looks they added up all of the peak outputs, not just the 12v rail. It also looks like they aren't being conservative in the least bit. It also doesn't sound that great considering that you would have to have a wall wart power supply to supply DC to the "power supply".

There are a number of ways to measure power output.

The generally accepted method is how much power all the rails can put out all at the same time, for a duration (continuous) and at a meaningful operating temperature (40°C or higher).

Some companies of course use different ways of measurement.

Peak output - What the rail can spike to, even if it can't sustain it.

Measured independently - Often a rail can put out more power if the other rails are not fully loaded.

Low temperature - The output of a PSU drops as temperature rises. Cheaper PSUs will be measured at 25°C (or temperature not even mentioned) since they can put out more power at those low temperatures. However, those low temperatures will (usually) never be seen during actual operation in a real PC and real environment.

Some companies use all those methods.

Also, some companies use pure imagination when coming up with wattage numbers.

Note that figuring out overall wattage based on just the +12v rail is not accurate. For instance some like to call Corsair's CX430 a 350W PSU due to the +12v. That is incorrect, as it can really put out 430W, just not all on +12v.

Now, if you are looking for a tiny lower wattage PSU, how about a SeaSonic SS-250SU? SuperBiiz has it for a reasonable price, and there's a 10% off coupon floating out there. Xbit Labs reviewed it. It did as well as any SeaSonic PSU, meaning it was reasonably efficient and put out rated power without fuss. The 40mm fan wasn't quiet compared to larger fans, but is probably reasonable compared to similarly sized fans.

Here's the label. You can see that SeaSonic "rates" it at 250W combined, even though the rails merely added up gives a much bigger number. For instance the 110W Max for the minor rails would otherwise be 131.2W and of course 110W + 216W /= 250W. There are some manufacturers who would call this a 400W PSU or higher (all numbers merely added up) even though 250W is what it can push out combined and continuously.

Thanks to the both of you. It does seem they just added up all the rails together, but it's still less than the combined +3.3V, +5V, +12V rails. If I do the calculations with the peak output then it manages to surpass 250W. I guess it's a really shady power board.

I thought most models base their wattage around the +12V rail, e.g. a PSU has 284W on the +12V rail so they may be conservative and "round" it up to 300 or 330W, due to the +3.3V and +5V rail providing some power too, but it seems the board I linked has been far from conservative. I emailed the seller before I made this thread up and lo and behold, I have not received a reply.

Really appreciate the link though Zap! My main experience of a Flex ATX was from using the pre bundled one with the Elite 100, and the fan on that was super loud, putting me off them. I also thought Flex ATX PSUs and TFX PSUs were the same until just now, I discounted TFX PSUs as SFX PSUs were smaller, and as I thought Flex ATX were the same as TFX, I ended up discounting them too.

The form factor of the SS-250SU is perfect for fitting alongside a mini ATX board as it's 150mm long as opposed to the mini ITX board's170mm. Looks like I may really be getting a build going!

Only problem is that in the UK, it costs a fair bit more. I've found it for £40 + P&P which isn't bad at all as it's roughly the same price as the Xilence 250W SFX which I was planning to get anyway. Looks like 250W is the sweet spot for me as my PC generally idles on around 50W and maximum load is 170W, which is 20% to 70% load respectively. I've got another plan where I can rebuild the case for the Flex ATX PSU out of acrylic with vents, along with a slim 120mm fan blowing over it so that it'll be quieter. Obviously that's a long way ahead though so it's still only a thought.

It is a sign of a shady brand, not necessarily a shady unit. However, one usually begets the other.

Yes, Flex ATX, TFX and SFX are all different form factors, though resellers have gotten creative in what they call these things, with Flex ATX becoming Mini ITX and SFX becoming Micro ATX even though those form factors don't exist for PSUs, AFAIK.

With TFX, SeaSonic makes really nice quality 80Plus Gold units up to 350W.

For SFX, SeaSonic is a bit behind the times.

It's more that the seller isn't telling all. The brand is perfectly fine and the powerboard is fine but what the seller isn't saying is it requires two AC adapters input to get the 250W. If you look on the right side of the powerboard there are two 4-pin inputs. This is a common confusion with this powerboard and a decent reseller of these products would have made that clear and known it.

I wish the SS-250SU, or something like it was available in a fanless version.