"With efficiency measured at 79.6% at 89.6W in our test, this Silentmaxx will probably reach 80% at 100W (20% load), so it too, can probably earn 80 PLUS certification."

20% of 400W is 80W not 100W. I guess this means it might not meet the 80 PLUS certification, though it's certainly right on the border.

Also, I wonder if the temperature difference can be accounted for because of a difference in testing. Looking at the pictures the Zen was tested with cardboard covering the top and the side of the power supply, while the Silentmaxx was tested with it covering only the side. Normally this kind of thing wouldn't matter, but with a fanless power supply I could see this small difference making a few degrees difference.

"The Zen earned 80 PLUS certification with >20% efficiency at 20, 50 and 100% of rated power (and >0.9 PF)."

A small typo, should be >80% efficiency, right?

Pink heatsinks ?
At first I thought it was a joke after the 'OMG ponies' Slashdot's design for April Fool's day.
Now I realizes it's serious, but I'm still not that convinced about the added benefit.
Sure, anything is better than silvery aluminum, but why not paint them black if it's to improve the heat radiation ?

I'll cast my vote for a measurement anomaly. More efficient heatsinks might keep internal components cooler, but they will not move less heat into the cooling airflow. Either the Zen allows significantly less airflow or SPCR missed something in the testing. I don't intend this as an insult; controlling secondary heat losses and accurately measuring the exhaust's average temperature can't be easy.

Yes, it's fixed now.

A silly question perhaps, but how exactly does the anodising process increase thermal radiation? It should actually have a negative effect on cooling, as the layer of aluminium oxide (which is thickened by anodisation) acts as an insulator.

Al2O3 wiki

Hello,

I don't know the reason that "pink" heatsinks help (they actually look closed to magenta to me), but the color reminds me of the color I see reflected from light bulbs, in the Low-E coating on my house windows. It is the part of the visible spectrum that is closest to the infrared (heat) range. So, maybe the improvement has to do with the heatsinks "reflecting" the heat from other heat sources inside the computer; rather than absorbing it?

It's just a guess...

How are the cable lengths as far as the Antec P180 is conserned. I am thinking the 2 of them be the idea match.

On reading I too paused to think about equating anodizing with higher thermal conductivity. I wondered "Hmm, is that some bit of convetional wisdom or even a proven fact I've missed?"

Isn't the general rule that energy tranfer slows down whenever it crosses a material boundry, in this case the oxide layer, as Jaganath above. Sigh, it is all a little far afield of anything I've truly researched and could speak definitively on ...

Could anodizing effect the airflow, I wonder? Like the laminar, fluid dynamics -- dimples on a golf ball & sharkskin swimsuits and all that. Might a sliicker, smoother, shinier anodized aluminum surface have less of a boundary layer of sticky air?

Mostly though, I look at this one and the Zen and think, "Wow, piece of cake to screw waterblocks onto those sinks asd whisk all that heat to a raditor outside the case." I have encountered PSUs where the heatsinks are electrically live though, making such an idea quite unwise .... Devon, could you check that on this ? Do a conductivity test between each of the 3 heatsinks and the AC mains and each DC line ? It would be nice to know before spending that much, hoping.

Actually, the article equated anodizing with higher thermal radiativity (if that is a word); the thermal conductivity of the aluminium should not have been affected, or marginally worsened by a thicker oxide layer.



I personally think the anodised layer is completely cosmetic. The kind of convoluted mechanisms by which we are surmising the anodising may improve cooling performance:

A ) wouldn't produce very large effects even if they were employed

and

B ) probably aren't employed on what is, after all, merely a humble computer power supply, albeit quite an expensive one.

From what I understand, the insulating effect of the aluminum oxide is minimal because the layer is so thin. Insulation needs to be thick to be effective.

The benefit of anodization is that it increases the amount of heat that is emitted via direct radiation (vs. convection) by several times compared to ordinary aluminum.

The question is, what proportion of heat is emitted via direct radiation, and what proportion is emitted via convection. I have been unable to find a satisfactory answer for this in regard to a system that relies on natural (passive) convection. It is certainly the case that the amount of heat dissipated by direct radiation is negligible in a system that relies on forced convection. This is why I left the speculation about the anodization open ended. I know enough that it should help in theory, at least a little bit, but I don't know how much. The physical argument that anodization is pointless is strongly made for systems with active cooling, but nobody seems to have looked much at passive systems. One other point about radiation: The amount of radiation increases with the temperature differential, which means that passive systems (which typically have a much greater differential) will tend to radiate more heat than active systems. Again, I'm not sure at what point it becomes a significant factor.

At the very least, I think the fact that almost every passively cooled piece of hardware I can think of is anodized (most are black anodized, which is supposed to be more effective than the pink anodization on the Silentmaxx) says something about the effectiveness of anodization in passive systems. To wit:

Zalman TNN series passive cases
mCubed passive HTPC case
Antec Phantom
The casing (not necessarily the heatsinks) of several other passive PSUs, including those by Thermaltake and Coolmax.
The Scythe Heatlane NCU-1000/2000 passive coolers

I think it's clear that the effects (if any) of anodization on cooling are poorly understood. My initial reaction was to write it off as a gimmick, but I've read enough that now I'm not so sure, which is why I left it in the article as a possibility. Perhaps someone with a deep understanding of the physics behind it can comment more.

Unfortunately, they're probably too short, especially the 12V AUX connector. I wouldn't risk it.

But you could still use extenders...right?

-Ken

If you're looking for fanless in the P180, I'm using a SilverStone ST30NF Fanless in one, and for my mobo cable lengths are okay.

interesting to see the use of multiple mosfets per HS - I believe this is was FSP used to spreadout heat output for the Greenpower, resulting in tiny heatsinks for the fanned PSU and bolt on bigger HS for the fanless one. Interesting to see how close (1-2%) the Greenpower and this PSU are in terms of efficiency up to 200W or so. I wonder what causes the higher efficiency at higher loads?

Actually, I believe that there are even more MOSFETs than in the greenpower. I count a total of 12 in the Greenpower, and 17 in the Silentmaxx. I believe the FSP Zen had a similar number.

I guess that'd make sense, particularly as components in fanless PSUs would have to be more tolerant of high temperatures.

After a bit of Googling it appears that anodization greatly increases the emissivity of the aluminium surface, depending on the thickness of the oxide layer of course. How and why it does this is still a mystery to me, at least. As you rightly point out, it would have been more effective to anodize the heatsinks black.

Physics paper discussing the emissivity of anodized aluminium in the context of window frames

Indeed, your link points to between 4 times and 17 times better emissivity after anodization.


You have Stefan-Boltzmann Law of Radiation (it's in the middle of that long page) : Energy radiated per second: H = e * A * omega * T^4
You want to increase H, keep T low (it's the temperature of the heatsink), omega is a physical constant. So you are left with A (the radiating surface) and e which is the emissivity
In our practical situation, you can't expand A too much size-wise, because it has to fit in the PSU. But you can increase the surface locally by giving it a rough finish. If the surface is rough, it increases the total radiating surface (/\/\/\ rather than ____ )

As to the emissivity, if the surface is closer to a perfect black body, it increases the heat radiated. With temperature found in a PSU, perfect applies to the ability to dissipate IR. I'm not sure if that's still regular black (which is perfect in the visible spectrum). Emissivity equals absorptivity if you believe Kirchhoff's law of thermal radiation, and we all know from day-to-day practical life, that under the visible light of the sun, black aluminum would be hotter than pink aluminim. So it's maybe a safe assumption to expand that to the IR spectrum and say that black would have been better than pink to radiate heat.

Hence the conclusion : anodized was good, but black finish would have been better than pink finish.
The question is to know if the pink is a painting or is anodized aluminium (I don't know the color it's supposed to look like). Is the pink easily removable, or does it seems embedded in the aluminum ?

Maybe they couldn't be bothered to paint it black, or the strange factor was supposed to make people believe it's better that way.

Said the marketroïd : "Black is so boring you know, you can't hype a 170$ PSU with black. Put pink in there, stupid engineer !" /rant

In your pdf, article 3.1 page 5 is especially important. They explain how a diffuse surface would be good for improving radiation. A rough finish does that a bit, but anodizing achieves that even better.

They conclude the paper with
"Further research should be conducted to find the emissivity of aluminum surfaces that have received other treatments, as for instance painted aluminum profiles." Maybe someone can find that paper, because experiment is always better than some theoritical rambling.

I bet its pink for some random reason. Someone liked the color or the equipment was set up to do pink.

It's pink and that makes me feel like a real woman. That's why I'd buy it.


The 200+ watter efficiency sounds really nice for those people who are attempting a x1900xt crossfire or sli setup. This would be great for a p180 in a power users/I spend money for reason/I drive an SUV/ setup. There are some of those out there you know?

Has everyone forgotten about SilentMaxx and their shady dealings? Their craptacular fanless PSU's known as the proSilence series?

Long story short, they don't return phone calls, emails, and DID NOT HONOR THEIR WARRANTY.

I RMA'd a dead proSilence 350, they took posession of it, and that was the end of it.

I posted a thread about SilentMaxx and their fraud here:
http://forums.silentpcreview.com/viewto ... ilence+350

-Ed

I suggest that everyone follow Edwood's link to learn more about his experience. It would appear that he got screwed when Silentmaxx' old distributor went belly-up. As far as I can tell, it was the warranty from the distributor that was not honoured. Silentmaxx itself is a German company, and would not be responsible for handling the warranty that he got in the US.

They can hide behind their distributors all they want, but in the end they put THEIR name on the product.

They do not stand behind their shoddy products, so I won't buy any product with their name on it.

-Ed

Just to correct a mistake: The primary side has MOSFETS in the PWM part, and to switch voltage on and off very fast. Because of the high frequency (several kHz compared to the mains 50/60Hz) alternating current so a smaller size transformer can be used.

The output side has diodes to rectify the voltage coming from the transformator.
The Zen (an this Silentmax labeled psu) has more diodes in parallel to lower the losses on those diodes. (the Green Power has 2 diode pairs on each (3.3, 5, 12) rail.)

(althougt the diodes could be replaced with mosfets and a control circuit to even more lower those losses, but usually PC power supplies are ancient designs.)

(In case you haven't already, i suggest you read this http://www.xbitlabs.com/articles/other/display/psu-methodology.html article on X-bit labs.)

Thank you for the corrections. I didn't look closely at the chips in question, I just assumed that the square black blocks of silicone were MOSFETs.

Just to clarify, the black blocks you see are just plastic. The silicon (as in semiconductors) is packaged within. This is different than silicone (which is used in caulk as well as boob jobs).

Thanks for the corrections. I do know the difference between silicon and silicone — that one's just a typo. Didn't know that the MOSFETs are encased in plastic though. What's the reason for that?

It's just a package to protect silicon from mechanical damage, corrosion and so on and ease installation of the device -- you can't attach silicon itself with screw, but you can put it on metal plate and make mount hole in this plate (remark: in some packages there is no metal plate outside, case is all-plastic, to provide electrical insulation from heatsinks without need to use additional insulation paddings).