be quiet! Pure Power 11 FM 750W Report (Page 4 of 4)

Page 4 - Minor Tests and Conclusion

Power supplies are interesting products, because often, reviews of products in this category are conducted and tested in methods that make it difficult to distinguish one power supply from another. Many aspects must be taken into consideration. Certain criteria consist of efficiency, noise, power ripples, and of course the ability to pull out the rated specifications. Because many cannot afford such equipment to obtain results regarding those aspects, articles covering power supplies often come out with less than adequate and acceptable information. As this is a product report -- not a review -- what we are doing is a close examination of the power supply and the internal hardware and build. But what we can do for you is do some minor testing with the results we can present to you with and let other review sites with professional equipment show you the actual test results. We are not going to try to create useless test results by installing the power supply into the latest gaming rig and try to take readings from that, as this is not even remotely the correct way to test power supply units. We understand that many websites do that as a means of load testing, but the results, even if you use an oscilloscope and multimeter at each output location, it is not sufficient, nor does it accurately reflect the performance of the power supply.

Using our power supply tester which exerts minimal load on the power supply, the initial consumption was 4W as measured by our wall meter unit, indicating that the basic load-free power consumption of the power supply was excellent. It ties with the SilverStone Strider Titanium ST80F-TI 800W and XPG Core Reactor 750W for the lowest we have ever seen. Independent reviews from websites with professional load testing equipment showed the be quiet! Pure Power 11 FM 750W delivered very good efficiency, voltage regulation, and ripple across all rails. This is an 80 Plus Gold certified power supply.

Voltages with minimal load are generally accurate, which is a basic requirement of power supplies out of the box. In this situation all are all within 2%. The PG or Power Good delay is tested at 180ms. This power supply officially supports Alternative Sleep Mode, so it is likely the PSU tester was not fast enough to pick up the true PG signal. The design specifications state it is required to be between 100ms and 500ms, with 250ms maximum for Non-Alternative Sleep Mode and 150ms for Alternative Sleep Mode.

Active power correction is important to correct AC load line loss. In AC power, there are three components to it; as there is a phase difference between current and voltage. This makes up the power triangle, which consists of the following: Average usable power (P, measured in watts), reactive power (Q, denoted as VA-R), and total power (S, written as VA). While they all have the same physical units, it is not the same thing as aforementioned. What we want is the average usable power with as little wasted reactive power as possible. The total power provided over the AC line is the magnitude of the two combined (sqrt(P^2+Q^2)). Power factor can then be easily calculated by P divided by S. The ideal value is 1.00, and this is where active PFC comes in. The be quiet! Pure Power 11 FM 750W has active PFC, and the power factor will approach 0.99 with a nominal load.

The be quiet! Pure Power 11 FM 750W is a very quiet power supply. Under regular loads up to 60%, the 750W Pure Power 11 FM is almost silent. Personally, I found the BQ QF2-12025-MS fan to be excellent, living up to the name of the brand. While this is very subjective, I am quite a picky person on noise. On a scale from 0 to 10 where 0 is silent and 10 is the loudest, I would rate the be quiet! Pure Power 11 FM 750W to be at 1.0/10 acoustically under nominal loads, because the fan spins really slowly. It is too bad it does not have a fan-stop feature, but this is as close as it gets. The fan is mostly out of the way even when the load increases, but as with all fans, it will become more audible as it spins faster. If you are a silent PC enthusiast, the be quiet! Pure Power 11 FM 750W is a very respectable choice thanks to the PSU's quiet fan curve profile.

be quiet! provided this product to APH Networks for the purpose of evaluation.

The be quiet! Pure Power 11 FM 750W is a power supply that lives up to what the name claims it is: Quiet, pure power. Crack it open, and you will find out it is built by Channel Well Technology with a reasonably good selection of internal components. It is compliant with the latest ATX specifications with a short PG time and, according to others with professional load testing equipment, has mostly delivered in performance. Power the Pure Power 11 FM on and you got a rifle bearing fan with a very low speed fan profile for very quiet operation. A 5-year warranty is commendable for a power supply of this class. Drawbacks of the Pure Power 11 FM 750W comes down to a multiple 12V rail design uncommon in modern power supplies of this wattage, 85c-rated main capacitor, and not a single Japanese brand capacitor anywhere at all. But for about $115 at press time, the price is very reasonable for an 80 Plus Gold certified fully modular PSU.

Page Index
1. Introduction, Packaging, Specifications
2. Physical Look - Outside
3. Physical Look - Inside
4. Minor Tests and Conclusion