What an awsome PSU.

A 12v PSU with what is essentially a PICO PSU bolted on for the non-12v lines, and throws out a lot of power with tiny losses, virtually no ripple, and in total silence.

Well done Seasonic, a masterful feat of engineering.


Andy

PS: My (now ancient) Antec Phantom 500 is still alive and in constant use (I think it might even be out of its 5-year warranty).

Could anybody give me an idea of what type of system you can run with a 400W PSU like this? E.g. could you run a quad core a single high end gfx card (perhaps not a fermi) and a 2-3 drives with it?

I'd like to see a case with a separate ventilated PSU chamber in the top.
Imagine a NSK-3480 with the rear half of the top chamber having mesh above and on the sides of the PSU. No need to have a solid cover when there's no noise.

Sure could, even with a Fermi. As a rough estimate, you could say up to 120W for the CPU/mobo/RAM and 10W each for the drives (assuming not super efficient 3.5" ones), that leaves you with around 250W for the video card and any minor things.

It's amazing how far we have come in last 5 years when it comes to PSUs. A great product Seasonic and it's nice to see you back where you belong, on top as the best PSU maker once again.
Thanks to SPCR for another interesting and usefull review.

The only real downside of this is the potential for accidents -- something like liquid or little bits could drop into the PSU. I suspect that with the 1-2cm spcae above the PSU in almost any atx case and the open venting of the back panel, unless you're red-lining the system/psu in a hotbox and hot ambient, it'd still be ok.

But that would run PSU very, very close to it's max which is something I would not recommend in the long run. And we are not even taking into consideration that upgrades would be hard and/or impossible without changing PSU also.

Don't forget that PSU age and loose ability to provide original amount of power with time due to capacitor ageing so to make a long story short it's a bad idea to not leave 20-30% headroom for growth and longevity when matching PSU with rest of the system.

Not to mention that your math is kinda off. Most AMD Phenom II are either 95 or 125W TDP alone, but you say that 120W is enough for CPU and motherboard ??! And if we go down Intel route ?

Intels new quads are also 95W TDP (or 82W in case of single I5-750S CPU).
It gets even worse if we look at the I7 series as most CPU there are 130W TDP and few with 95W and 2 with 82W TDP.

http://ark.intel.com/ProductCollection. ... Segment=DT
I5 Specs

http://ark.intel.com/ProductCollection. ... lyID=28037
I7 specs


As you can see you are mistaken if you think that this PSU would be good choice for running a modern quad with a Fermi card and giving somebody else advice to do just that is....shall we say irresponsible ?

Thanks Mike great review, glad you change your mind about this fanless baby!

Great efficiency for an office build, the x-650 was an overkill for my needs.

I wonder where is the best place to put it: at the bottom like in p180's or on top with a hole on the case

wow....just wow.

On top of course, heat rises, and you would be a bad comp.builder if you did not took advantage of natural heat convection

In a word: superb.

A case that has a open top/vent over the PSU is what this PSU would be best in? Mike, any plans to use this in a system; fanless or otherwise?

Maybe my system is not modern enough but I'm running Q9450, 8GB ram, velociraptor and another hard drive and a 460gtx 1GB @763MHz/1900MHz (stock oc) and it draws just around 200W from the wall when playing just cause 2 and about 90W idle. I don't think this psu would have any trouble with my system and in fact I use a corsair 450W psu with it.

Excelent PSU, and review. thanks. The Seasonic X sieries is looking really good.




Sadly its been true for silent/quiet system builders as well. If you look at the SPCR recommended list there is only one sub 500W PSU on there (Nexus) and most of the rest are 600W or higher.
Considering most maistream useres build systems that require 200-300W on load I'd like to see more+better PSUs with 400W-500W printed on them.

Great review, and another excellent product from Seasonic.

Kind of OT, but Mike, would you happen to know if Seasonic has any plans to release an 80Plus Gold SFX power supply in the near future? If it wouldn't be too much trouble, maybe you could inquire to one of the reps you normally speak with. I contacted Seasonic about a month or two ago about this, but never received a reply. The SS-300SFD in my NSK-3300 is getting a bit long in the tooth, and I was thinking about how nice it would be to replace it with an 80Plus Gold unit, especially if they can build an SFX unit that has similar noise characteristics to the ATX form factor X Series PSUs. Unfortunately I don't think I have the room to fit an RM112 or anything like that in the top compartment, it's just too long.

Awesome!

Great review and great product!

I'm wondering how I can fit it into my Solo case, what's the air flow for traditional ATX case. Should I reverse it?

This is an amazing psu and also great review Mike! I really like how the OTP was able to protect the psu from dying in extreme conditions. I feel like a lot of the psus out there list protections, but don't actually provide many of them.
I'm going to strongly consider an X-560/660 for my next pc build next year because I'm still a fan of fans, especially very low rpm ones that are quieter than other parts such as hard drives.

This thing is spectacular.

Pricey, but if you want the best...

I think the hot air will be keept inside and the pcb will warm up, that's why they put an mounting advertising on it.

The best way for the solo is maybe to cut a vent on the top of the case just under the top vented panel of the psu.

To be honest, I'm not even sure it's that much. My computer doesn't use a hair above 200W load, and I have the CPU and GPU overclocked. I can't see too many mainstream users using more than 200W on average. And it's funny because so many of them will go out and buy 700W+ psu's cause they think it will help them somehow..lol

I'd personally start with the recommended position, and if the PSU seems super hot (like >60C at the back all the time), then try it the other way. On the other hand, because the vented back will be the the easiest hot air exit path, that's where it will go... and you may get really high temp readings there all the time... but actually, no. If you have a typical system w/ hot dual video cards, I'd guess it'll be barely warm to touch most of the time.

Am I the only one who would purchase this unit over the PICO for a very low power system (in the range of 25 to 50 or 75)? Even though it is twice as expensive?
I really like my PICO, but the Seasonic has more hookups with a five year warranty and quality indicates it will likely last much longer than the warranty period. Since I live off the grid efficiency is very important to me, but at these outputs a difference in Calculated Efficiency of maybe two percent is not significant. It just seems a better long term investment.

Well, considering the price, i don't see a point of buying this vs the X-650. Take a look - US$139, that is $165 with 19% VAT (the typical VAT in Europe), converted to € it is 128 euros. Add a profit for the seller to that and we are at 135-140€ range. Seasonic X-650 is 130€. So unless you hate to have a fan in your case, there is no point buying this vs X-650 for typical use.

Even in USA the pricing is same - X-650 on Newegg is $139.99 vs suggested price in the article for X-400, which is $139.

Mike, thanks a lot for your suggestions!

I agree that it's difficult to imagine what's the best before get one and try it. I'm very curious about the "Attention: this side up". For passive PSU, it's very important to have the proper air flow in case. Meanwhile in nowadays, PSU can be anywhere, up or down. I suppose Seasonic did comprehensive investigation for different cases, unfortunately the knowledge is not shared but just a simple warning.

I don't have a hot video card (E8300+HD3650), the measured system AC power (PSU is Antec EA-380) is just 65W in idle and 130W in CPU+GPU load. I'm going to update my system to be somewhat like SPCR Model One, except use X-400 as PSU and HR02 as CPU cooler, then I have single 800-rpm fan left. Hopefully both of them can be available in September.

I'm in agreement. picoPSU is really optimized for <100w load -- higher, and it's working out of its optimal zone, with both price and performance affected. But no 12VDC adapter + picoPSU can give you x-series quality regulation or protection.

As for pricing, yeah it's not cheap, compared to a typical premium 400w fan-cooled unit, but look at the price of a Silverstone ST40NF, the closest competitor but w/ older, less efficient design. Typically, it's $160~170.

And there's absolutely no question the x400 can deliver >500w peaks. I did mention that the guts of the psu can be rated >700w if fan cooled.

typo -- I meant to write w/o, not w/.

You don't need a 30% reserve and to use the TDP. The TDP is well over what a CPU will use in normal usage. The only way you'll see TDP is if you leave the stock CPU on and run multiple threads of a CPU burn type program plus add a graphics program to the mix.

Add a non stock heatsink of the >700g variety and ventilate the case properly and your CPU won't hit the TDP unless you overvolt it.

Just because a CPU says 95W doesn't mean it will ever draw 95W take a serious look at the data on http://www.silentpcreview.com/article1056-page2.html and you see:

AMD X4 630, 95W TDP, 82W at load
AMD X3 440, 95W TDP, 78W at load
AMD X3 435, 95W TDP, 75W at load
AMD X3 720, 95W TDP, 71W at load
AMD X2 255, 95W TDP, 57W at load
AMD X2 555, 95W TDP, 57W at load
AMD X2 250, 95W TDP, 50W at load

Sure you can think worse case and treat all of these CPUs as 95W but you'd be giving way more than a 30% overhead on some of these. (The range is actually 14% to 48% overhead gained by treating all of these as 95W).

Similarly with Hard drives or SSDs your highest power draw is likely to be during the OS boot process when the CPU is mostly idle. When you stress the CPU and video card the drives are likely not going to be busy for more than a minute or two at a time.

So if a HD takes 9W at load and 5W at idle you already have another case where treating it as a max wattage device builds in more than 30% overhead in 99% of the usage case scenarios.

Lawrence Lee (SPCR reviewer) took these components and the CPUs I listed above and couldn't get it to break 132W

# Asus M4A78T-E motherboard - 790GX chipset
# Corsair XMS3 memory 2x2GB, DDR3-1600
# Asus EN9400GT Silent Edition graphics card - 512MB
# Western Digital VelociRaptor hard drive - 300GB
# Seasonic SS-400ET ATX power supply
# Microsoft Windows 7 operating system - Ultimate, 64-bit
# Scythe Kabuto CPU cooler

Even with a quad core CPU he never got even close to 150W let alone anywhere close to 70% of 400W. Even leaving a 30% safety margin you only need to stay below 280W during stress testing.

A GTX 460, 465, or 470 could slide in under that limit after you take the old 9400GT out.

And believe me you could make MUCH BETTER choices in components and leave even more head room.

As you can see treating components by maximum power draw and then asking for 30% reserve on top of that is clearly bad math. I won't call it irresponsible, I'll just call it a waste of money with a dash of fear, uncertainty, doubt (FUD) thrown in.

Measure real world usage and add 30% or use TDPs and don't add 30% but don't do both.

The comment about going up to 700W with a fan is interesting. Makes me wonder why they don't release a version with a fan that only kicks in above 400W. With one of the 5000 series Radeons and a modern 6 core CPU you could have a system that runs fanless in normal use but can ramp up to heavy processing or games easily.

You still wouldn't see more than 250W at the wall....unless you have a crossfire setup or you only run Furmark and Prime95 as your apps.