PSU Fundamentals & Recommendations

shanizar · Post by **shanizar** » Wed Oct 19, 2005 9:23 am

didn't want to seem like I was complaining as I wasn't

I live in Norway, and getting my hands on the right PSU's isn't easy at all...

Post by **MikeC** » Wed Oct 19, 2005 9:31 am

shanizar wrote:didn't want to seem like I was complaining as I wasn't I live in Norway, and getting my hands on the right PSU's isn't easy at all...

No problems, mate.

shanizar · Post by **shanizar** » Wed Oct 19, 2005 9:51 am

well, now that I have you here I might as well ask your advice (and the advice of anyone else here who wants to give it).
This thread details a computer I'm building and that is going to be placed in our bedroom. After going from the silentium case to an Antec SLK3000B based on advice, I now need to find a power supply. I guess the Fortron isn't good enough, but I found a norwegian webshop that sells the Antec Smartpower 400W (pre-installed in the case) and a Nexus NX-4090 400W.

Which would you say is best for my system? According to the recommendation, the Antec gets the best score, but according to the dB listing in the reviews, the Nexus is best...

Post by **MikeC** » Wed Oct 19, 2005 11:26 am

Reply in your other thread, shanizar (to keep this one on topic).

Post by **MikeC** » Fri Oct 28, 2005 7:05 am

Minor updates & corrections made to the Recommended Lists.

Brians256 · Post by **Brians256** » Fri Oct 28, 2005 9:56 am

MikeC wrote:Minor updates & corrections made to the Recommended Lists.

Another correction:

Last page, "Link to Antec P150 Mid Tower case review. (It comes with a Neo HE 430 PSU.)" points to the PSU review, not the P150 review.

BTW, long time admirer of SPCR work. Great job, guys.

Post by **MikeC** » Fri Oct 28, 2005 10:07 am

Brians256 wrote:
MikeC wrote:Minor updates & corrections made to the Recommended Lists.
Another correction:

Last page, "Link to Antec P150 Mid Tower case review. (It comes with a Neo HE 430 PSU.)" points to the PSU review, not the P150 review.

BTW, long time admirer of SPCR work. Great job, guys.

Ah, thanks for catching that. Fixed.

Tephras · Post by **Tephras** » Fri Oct 28, 2005 2:20 pm

MikeC wrote:Minor updates & corrections made to the Recommended Lists.

Just noticed that in the fanless PSU table the link for the Fortron Zen review is pointing to the Antec Phantom 350 review and the link that, I assume, should be pointing to FSP Group is pointing to Antecs site.

Post by **MikeC** » Tue Jan 03, 2006 11:20 am

Updated again, mostly just the lists: Jan 3, 2006 - Zalman ZM460-APS, Fortron Green 400W and Seasonic SS300-SFD 80 Plus added. Enermax Noisetaker 325 & 475 retired; Antec NeoHE430 retired for now -- until proven reliable.

Ackelind · Post by **Ackelind** » Tue Jan 03, 2006 12:11 pm

Why not add the Neo HE to the list somewhere? It was reviewed separatly.

Post by **MikeC** » Tue Jan 03, 2006 12:28 pm

Ackelind wrote:Why not add the Neo HE to the list somewhere? It was reviewed separatly.

jaganath · Post by **jaganath** » Tue Jan 03, 2006 1:07 pm

Why not add the Neo HE to the list somewhere? It was reviewed separatly.

I think SPCR is very wise to temporarily withdraw its recommendation from the NeoHE 430 until such time as the current problems with various makes of motherboards are satisfactorily resolved. A lot of the kudos that comes with an SPCR recommendation is derived from the fact that recommended products are generally of a very high quality with little in the way of compatibility or build quality problems (like the Seasonic S12 range for example). IMO the NeoHE has not yet shown it can live up to these high standards consistently.

HammerSandwich · Post by **HammerSandwich** » Tue May 30, 2006 7:14 am

In light of these power numbers at Tom's, I think we should note the increased power draw of overclocking.

Noli · Post by **Noli** » Mon Jul 24, 2006 5:18 pm

Could we get reviews of the OCZ GameXStream 600W & 700W PSUs please? Especially vis-a-vis the Seasonic S12 600W. Just that I've read many reviews that wax lyrical about how quiet the new OCZ PSUs are, especially for such a powerful PSU. Of course, what I would love to know is how quiet are they in the eyes of SPR analysis and vs the competition? Also, given that a 120mm fan mod looks easy on the OCZs, a) is it? with a Nexus of Scythe S-Flex for example? and b) how would that affect it and its standings for noise?

Any comments to this note appreciated

Oleg Artamonov · Post by **Oleg Artamonov** » Tue Jul 25, 2006 10:35 am

Ambient temperature 22C.

jaganath · Post by **jaganath** » Tue Jul 25, 2006 11:48 am

Given that the OCZ GameXStream fan spins almost twice as fast as the S12-500 fan at all points along the output curve, in stock form it's no contest noise-wise. However OCZ quote 83% efficiency on 230V AC, so there is probably good potential for a fan swap to improve noise.

Post by **MikeC** » Tue Jul 25, 2006 12:29 pm

jaganath wrote:Given that the OCZ GameXStream fan spins almost twice as fast as the S12-500 fan at all points along the output curve, in stock form it's no contest noise-wise. However OCZ quote 83% efficiency on 230V AC, so there is probably good potential for a fan swap to improve noise.

Why bother? The S12-600 is about the same price as a GameXStream 600.

Noli · Post by **Noli** » Tue Jul 25, 2006 3:44 pm

Thanks Oleg and others. BTW Oleg, have you got a link for your graph or was it constructed yourself? Thks.
I guess the Seasonic is convincing given the backing it has by so many here - shame it hasn't got nice sleeved cables but the noise factor is more important.

Oleg Artamonov · Post by **Oleg Artamonov** » Tue Jul 25, 2006 4:02 pm

Article with this graph will be published at xbitlabs.com... mmm... may be at the end of august

Yes, it was constructed by myself

Actually, OCZ GameXStream made by FSP and almost identical with FSP Epsilon, but Epsilon is much quieter. I asked FSP Group did they change fan speed controller in all their Epsilons (new revision?) or for OCZ only, but there's no answer yet.

Tephras · Post by **Tephras** » Tue Jul 25, 2006 5:26 pm

Noli wrote:I guess the Seasonic is convincing given the backing it has by so many here - shame it hasn't got nice sleeved cables but the noise factor is more important.

Seasonic upgraded the S-12 series quite recently, the PSUs now have sleeved cables, here's a pic from the SPCR review of the S12-330.

msde · Post by **msde** » Mon Aug 07, 2006 1:56 pm

I've always tried to approach silent computing by attacking the source of the problem, heat. Or, in other words, power consumption. Is there any way to tell whether one recommended PSU is more efficient than another? Or should I just grab an 80+ and call it a day?

Post by **MikeC** » Mon Aug 07, 2006 2:51 pm

msde wrote:I've always tried to approach silent computing by attacking the source of the problem, heat. Or, in other words, power consumption. Is there any way to tell whether one recommended PSU is more efficient than another? Or should I just grab an 80+ and call it a day?

Of course. Check any SPCR power supply review. We've review a lot of them, many of the best, imo.

Post by **MikeC** » Mon Aug 14, 2006 10:27 pm

Minor update, just to the recommended tables.

HueyCobra · Post by **HueyCobra** » Sat Aug 26, 2006 1:16 am

Thanks for the update

Just checking with regard to PFC and energy efficiency on the fanless Silverstone ST30NF:

... along with Active PFC, a big plus for energy efficiency.

However on the previous page of Power Supply Fundamentals & Recommendations:

Does PFC make a power supply more efficient? No , the power factor correction is usually applied by an input circuit which uses a small amount of input power. With two PSUs that are identical, equipping one with PFC will cause a typical efficiency drop of 2~4% ... APFC is usually found on higher quality PSUs, but the two are not intrinsically related.

jaganath · Post by **jaganath** » Sat Aug 26, 2006 6:38 am

They are both correct; PFC itself does not improve a PSU's efficiency, but it improves the overall energy efficiency of the electrical grid, because devices with power factors <1 cause more resistive losses in power transmission lines.

Post by **MikeC** » Sat Aug 26, 2006 6:52 am

HueyCobra --

You're right, that was probably confusing for lots of people.

The text "...a big plus for energy efficiency" has been removed, and the answer to the question Does PFC make a power supply more efficient? has been expanded:

Not in the normal way that power supply efficiency is defined, which is the power loss (to heat) as a percentage of total AC input in AC-to-DC conversion. However, in the sense that Apparent AC power (VA) is lowered, PFC does reduce energy consumption.

Power factor correction is applied by an input circuit which uses a small amount of input power. With two PSUs that are identical, equipping one with PFC will cause a typical efficiency drop of 2~4%. Many PSUs that have Active PFC also have high efficiency, as APFC is usually found on higher quality PSUs, but the two are not intrinsically related.

I also took a closer look at the discussion of efficiency at the beginning of the article... and found that nowhere is efficiency explicity defined. I've corrected that oversight with the following, on the second page:

What is efficiency in a power supply? It is defined as the power loss in AC-to-DC conversion, expressed as a percentage of total AC input power. For example, a power supply that requires 100W AC input to produce 70W DC output has an efficiency of 70%. In this example, 30W is lost as heat within the PSU. A power supply that requires 100W AC input to produce 80W DC output has an efficiency of 80%. 20W is lost as heat. The 10W difference in these examples seems trivial. However, at higher output levels, differences in efficiency becomes quite significant in terms of how much energy is lost as heat, as the table below shows. The ideal efficiency is 100%, where AC input and DC output are the same, and there is no loss to heat in the power supply.

The table mentioned above shows the power lost as heat at different efficiency levels.

HueyCobra · Post by **HueyCobra** » Sat Aug 26, 2006 7:47 pm

Thanks very much for the clarification, Mike

Post by **MikeC** » Thu Aug 31, 2006 4:07 am

Aug 31/06 update-- Updated much of the text on Intel PSU guidelines based on latest Power Supply Design Guide for Desktop Platform Form Factors (Revision 1.0 - June 2006). Also expanded discussion on multiple 12V lines, efficiency, power factor correction, etc.

dhanson865 · Post by **dhanson865** » Thu Aug 31, 2006 4:57 pm

This image is from page 4 of one of the classic articles on SPCR.

I wonder if that section shouldn't be modified. It seems that average newcomers to SPCR are going to be most concerned with the 100 to 200 watt range.

If you comb the various SPCR articles and make a seasonic to seasonic comparison instead of seasonic to enermax you see:

At 90w the S12-430w has the best effeciency
At 150w the S12-430w has the best effeciency
at 200w the S12-330 and S12-500 tie for best efficency but the s12-430 is so close it's a non issue.

Code: Select all

Model       Output (W)  65      90      150     200     250     300     400     500     600

S12-330     Efficiency  75.5%   77.9%   80.3%   82.0%   80.9%   79.9%   **
S12-430                 78.3%   80.5%   81.6%   81.8%   80.5%   79.6%   *
S12-500/600             75.1%   78.0%   81.2%   82.0%   81.8%   81.1%   79.0%   79.7%   78.9%

Enermax 600             69.4%   73.8%   78.9%   80.2%   80.5%   80.3%   78.8%   76.5%   73.6%
(Enermax NoiseTaker II (Revision 2.2))

Shouldn't the chart and discussion on that page of the article reflect the sweet spot of effeciency around the 400w rating area? Or is the margin of error in the S12 series articles too close?

Or at least reflect what it truly is? Because all that chart does is compare an efficient PSU with a less effecient PSU. I.E. too many variables and not enough controls.

Would it be better to compare a cheap 300w PSU with a cheap 600w PSU or to compare S12-330 to S12-600? I don't know, but I have always found that part of the article to not hold up when I read the reviews of better power supplies.

Post by **MikeC** » Thu Aug 31, 2006 5:18 pm

dhanson865 wrote:I wonder if that section shouldn't be modified. It seems that average newcomers to SPCR are going to be most concerned with the 100 to 200 watt range....

...Shouldn't the chart and discussion on that page of the article reflect the sweet spot of effeciency around the 400w rating area? Or is the margin of error in the S12 series articles too close?

Or at least reflect what it truly is? Because all that chart does is compare an efficient PSU with a less effecient PSU. I.E. too many variables and not enough controls.

Would it be better to compare a cheap 300w PSU with a cheap 600w PSU or to compare S12-330 to S12-600? I don't know, but I have always found that part of the article to not hold up when I read the reviews of better power supplies.

The two items were chosen for comparison because it shows clearly what is meant by correct PSU sizing, which is the main thrust of the text in that section. Both of the PSUs are high efficiency. Lots of people have posted (and continue to post) in the SPCR forums about whether they should be getting a 500W or 600W model when in fact the details of their systems suggest maximum peak loads of <300W. This is precisely what the comparison was meant to address. I don't see how and why you think it does not hold up. It's a simple comparison.

PSU Fundamentals & Recommendations

OCZ GameXStream 600W & 700W

OCZ vs Seasonic

Re: OCZ vs Seasonic

Aug 31/06 update