If you have a dual chamber case like the P18x series you'll have a fan pulling air through that chamber even when the PSU fan is off.

If you have a traditional case the fact that heat rises will mean any air pulled inwards will stay higher in the case and end up going out the rear exhaust fan with little to no effect on other components unless you have a VERY TINY case. If your case is that small you'll have airflow issues anyway.

Also keep in mind the fan is thermally controlled not based on wattage. If the case is thermally challenged the PSU fan will come on sooner.

besides if you don't buy one maybe the price will drop so I will buy one.

I've just begun building a system with an X-750, and it's currently running Memtest on a bench in the basement without a case. With load at 175-180W AC & ambient below 20C, the fan turns on for roughly 10 seconds every 2-3 minutes. The fan speed is so low it hardly matters, but I'm not sure why this configuration produces such different results than your review setup.

What if it is 32 degrees C out? Aka: Summer? please no one say "air conditioning as this A) is 900x noisier than any psu on the market B) is a waste of electricity (especially since I live near an ocean).

I don't think my room is ever much below 77 degrees/25 C. 24/7 use keeps things warm, and then you hit a game, I duno. I am having doubts about this psu now.

might go Nightjar

Maybe this is the difference:

Cherry picking company?

What is the rest of your system spec, though?

Unless it's identical to the SPCR test rig you can't expect the same results, and to be honest the ambient room temperature is completely irrelevant here - it's the temperatures inside your case that will affect the PSU fan speed.

This fanless-mode idea is ambiguous and won't suit Holy Grailers.

First Prize in the Most Absurd Thing I Read on the Internet this Year

The amount of cooling from air depends on it's humidity and the temperature differential between the air and the object being cooled. The ambient air temp is the temp of the air going into the case.

Why do you think that the highest expense for a data center is AC? It's for cooling the air going into the servers, aka, ambient temperature.

I am going to completely re-work my reply here. I didn't realise there was an in-depth discussion going on about air conditioning and room ambients previous to this post. I was just responding directly to the last post, also not seeing this was perhaps an experienced/regular forum member taking part in a larger discussion.

It sounded like someone just trying to work out why their PSU fan was coming on even though their ambient temps were similar to the SPCR lab during the test. I was trying to cut to the chase and get the case temps as this is the environment the PSU is operating in directly, not in the ambient air. Yes the ambient air plays a big part on determining the conditions inside the case (I admit was a bit over enthusiastic in using "completely irrelevant"), but that alone doesn't tell us anything about whether or not the cooling inside the case is adequate or if there is heat build up.

Try not to get too worked up

As noted in my post, there is no case at this point. The ambient is definitely below 20C, though I've not measured it. I'm not sure how the rest of the system could affect the PSU's heating & cooling at a 180W load, but...
* Gigabyte GA-P55-UD4P
* Intel Core i7-860
* ATI Radeon HD 5870
* 8GB PC3-1600
* WD 750GB Caviar Black
* Xigmatek HDT-S1284 HSF
* no case

Sorry, I don't know how I completely missed that part of the post

Joseph Black would still be disappointed with you.

That seems a bit odd... but it is possible this was happening in the test setup too. We may not have noticed it because the PSU fan was mostly not visible during testing.

The PSU in the test rig faces down, as if it is in a standard tower case, and its fan is not visible -- the "case exhaust fan" had to be removed and a strobe light pointed up through that opening to check the fan speed periodically for this PSU (because we could not do straight voltage monitoring due to pwm).

However, as you point out, "the fan turns on for roughly 10 seconds every 2-3 minutes. The fan speed is so low it hardly matters." We may not have noticed because we weren't looking at the fan continuously and it isn't audible anyway.

A relevant question would be: At what power load does the PSU fan come on and stay on continuously, and when it does, how loud is it? My guess is that this would be the 340W load we found in our test (or similar anyway -- there are almost always some sample variances).

crappier efficiency Nightjar ftw.

It aint silent if it has a fan stuck on it.

Most reviews never keep a system on enough to get all of the parts heated up. I know the hotbox is a great way to see how things go under heat situations. I have noticed over the course of months, psu's ramping up more and more often with same usage and components.

179 dollar nightjar is "out for delivery". If it doesnt cut the butter, I will try the x-650.

I'm happy to accept that as a reasonable enough explanation.

No problem. And, hey, you took it well.

heh. I really should have taken a wattage reading before i replaced my power supply. Seeing as I have my pc on 24/7, the money saved might have been quite interesting, especially as my S12 500W was 2 years old, and its efficiency would have gone down quite a bit.

Basically i might have have been able to produce a justification for splashing £130 on a new PSU when my old one worked just fine, but i missed the opportunity. It really doesnt seem worth the effort to hook the old one back up just to check.

Will the 550LT ever show up? It's been >7 months since I started looking for it.

I'd like to echo my interest in the answer to that question. I have a similar system I'm building to Hammer's (smaller video card, though -- and I'm putting it in a case ) I'd like to have the Gold/silent/modular X650, but I'm not finding it available for even $150 at the moment. While it seems to be more efficient than the Nexus-430 even at my low (assumed) idle, I'm finding it hard to justify an extra $100 or so premium for a few percentage points and the cleanliness of modular cables. I'm trying hard, mind you....

I'm fascinated by the 550LT's pics (that would be from the links to the 80plus report, which I can't link to because I'm new here -- see dhanson's post). Where's the fan on that thing? Did they take a pic of the thing fan-face down? Doesn't look modular either, which is a shame (cables look clumped to one side).

The "simulated sine wave" issue is a myth. Truth is usually there isn't any problem at all, substantially it was a problem of some old Enermax PSUs only (Liberty, Infiniti and Galaxy series), because of some weak capacitors they used for their active pfc implementation.

It's not modular. The fan is in the same position as on any other Seasonic PSU they just took the pic from an angle that doesn't show the fan.

I'm getting tired of waiting for the 550W Gold model. Just noticed that the S12D-750 is $115 at newegg and the 850W version is $120.

That makes it cheap enough to get the Silver 750W instead of the Gold 650W and as long as you aren't breaking 200W ever under any circumstances (which is true for all the PCs in my house) I don't expect to be able to hear the difference.

The savings of $50 up front will outweigh the extra half a percent efficiency at the loads I'll use making the Silver more cost effective over the life of the unit.

The only down side is that it has 4 PCIe connectors and I'll only need 1 at most for any video card I'd buy. So I'll have some cable clutter. But to save $50 I'll tie up some cables and shove them out of the way.

Nice. Best I found X650 was at excaliberpc. From what I can see there, looks like the "Gold" premium is $20 (a bit more, really, considering the downsize in watt rating), and the modular premium is about the same. Everyone has to make their own decision as to whether either is worth it.

Hello SPC users

I was wondering if this Seasonic power supply (either 650 or 750W model) was tested on a 230 or 240VAC line and what was were the efficiency numbers for @ 300W AC load.

BTW I've seen the numbers for a 542W AC load but I'm curious about the efficiency at lower load on 240VAC.

TNX in advance, cheers

Hi,
in the x650 How long are the cables?
on internet I cannot find an answer.

In my cabinet p183 I have a problem with my psu (xspice) that has the cable for 4 pin EATX12V (look at the top of the MB) of only 20"...

I would fit all the cables in the rear of motherboard... but seems hard.

Thank you!

This is from the SPCR review:

doh! I waited a few days too long and newegg sold out of the S12D. Guess I'm stuck paying the extra for a Gold 550W or 650W now.

thank you !

What is it that stops you from buying a proven and tested Corsair HX650W? It's known to be quieter than those S12s. Seasonic-made too!

Take a look at the name of the thread. The X650W is Gold rated. At $40 cheaper the S12D-750 was silver rated. The HX650W would have to be cheaper than that to make me consider a Bronze rated unit.

Though a review by a trusted source and a price adjustment might get me to reconsider it the HX650W isn't even on my list right now.

I know what the thread is about, I didn't recommend the Corsair over the almighty X-650, only over the S12D you are so eager to buy. Efficiency difference according to 80Plus itself is a meager 1% at full load, and the Corsair is a modular unit. You should also consider what's the range you're using it in, as the two could easily have the same efficiency at your target load.
Also, the Seasonic is much more expensive where I live, so my recommendation didn't account the price premium you have to face in the US.