X-650: Seasonic hits Gold

Power
Viewing page 5 of 6 pages. Previous 1 2 3 4 5 6 Next

8. FAN, FAN CONTROLLER and NOISE

The PWM controller and the absence of a fan speed monitoring line made it very difficult to determine the speed of the fan at various loads. Only two points were determined: Speed at fan turn on was 440~480rpm, and it was 1900rpm at full power. However, the reason the fan speed is monitored in the first place is for the noise, and the key parameter, SPL, was measured at several points through the load testing.

The PSU fan did not spin up at turn-on with a 20W load. In fact, it did not spin up immediately at turn-on even with a 200W load, at least not from a cold start. With the fan not running, the X-650 could be deemed silent. There was no measurable noise from a meter distance in the anechoic chamber. From under 1' distance, a touch of coil and capacitor whine could be heard, but it was a trace amount no higher in level than any other PSU. The fan started spinning about 10~15 minutes into the 150W load test. The 440~480rpm fan speed measurement is an approximation; there was no way to keep the thermal load unchanged and measure fan speed simultaneously.

The X-650 proved to be the quietest power supply tested, at loads up to 300W. It was very quiet at higher loads as well, but between 300W and 500W, its fan ramped up a bit quicker in our hot box than a few other previously tested quiet champs. Still, it was still very quiet, barely exceeding 30 dBA@1m even at full load. Through much of the practical load range for a 650W PSU — 40W~300W — the unit did not venture beyond 16 dBA@1m in our hot test box. In one of the modern advanced ATX cases with the PSU well insulated from the heat of the other components, the fan of the X-650 may never spin up at such loads.

The screen captures below from our SpectraPLUS audio spectrum analyzer should be self-explanatory. Note that the noise floor of the anechoic chamber is just under 11 dBA. The red line is the ambient level of the chamber without any noise sources.


With the fan spinning slower than 500rpm at 200W, the overall noise of the Seasonic X-650 was virtually identical to the ambient acoustic in the anechoic chamber. Only the tell-tale spikes (at just -10 to -15 dBA) above 10 kHz indicate the presence of power electronics in the room.


At 250W, the fan became more audible but it was still extremely quiet.


Not much change at 300W.


SPL crested 30 dBA@1m at 400W load; this was about as noisy as the X-650 got. At full load, it measured 32 dBA@1m, presumably with the fan at full speed.

One question asute readers will ask is, "Does the fan stops spinning when the load drops?" This is an issue we've seen in other "semi-passively cooled" PSUs: Once it starts, the fan simply does not stop spinning even when load drops way below the load which triggered it to start. The answer is, YES, the fan in the X-650 did stop when the load was reduced below 150W — but not instantly. How quickly the fan stops depends on how quickly the heat is dissipated from not only the PSU but also the case. In testing, this was checked by dropping the load after the fan started, from 200W to 90W. With the "case fan" in the test box at very low speed (~600rpm), the fan in the X-650 stopped after about 2 minutes. Exactly when it stopped was difficult to determine because the fan was running so quietly before it stopped.

Another question some readers will ask is, "To what power level will the fan remain unmoving and silent when the X-650 is used in a case like the Antec P182 (and similar) where the PSU is well insulated from the heat of the other components?" In anticipation of this question, a second load test run was done with the X-650 outside the hotbox, as with the Antec CP-850 PSU.


2nd load test run with X-650 out of the hot box.

Seasonic X-650 SPL: In Hot Box vs. Out
Power load
90W
150W
200W
250W
300W
400W
500W
650W
in hot box
<10
<10
12
14
16
31
31
32
out
<10
<10
<10
<10
<10
16
27
32
Measurements are in dBA@1m

On the test bench with ambient room temperature at 23¬įC, the fan in the Seasonic X-650 started at about 340W load. Naturally, it was much quieter to a higher load than inside the hot box. It was quieter at lower loads and slightly noisier at higher loads than the only other PSU we've tested in this way, the Antec CP-850.

Antec CP-850 SPL: In Hot Box vs. P183 case (guesstimate*)
Model
90W
150W
200W
250W
300W
400W
500W
700W
850W
in hot box
12
12
12
14
14
26
40
44
45
out
12
12
12
12
12*
14*
20*
24
40*
Measurements are in dBA@1m
*These points are guesstimates; the rest were measured.


COMPARISONS

The comparison table below shows the SPL versus Power Load data on all the PSUs tested in the anechoic chamber thus far.

Comparison: Various PSUs Noise Vs. Power Output in Anechoic Chamber
Model
90W
150W
200W
250W
300W
400W
500W
6-700W
850W
Seasonic X-650
<10
11
12
14
16
31
31
32
n/a
Nexus Value 430
11
11
16
18
18
19
n/a
n/a
n/a
Antec CP-850
12
12
12
14
14
26
40
44
45
Seasonic M12D 850W
14
14
14
14
14
24
37
42
42
Enermax Modu82+ 625*
13
13
14
15
16
26
36
37
n/a
Coolermaster M700W
14
14
18
21
25
27
34
34
n/a
Chill Innovation CP-700M
15
15
15
15
17
30
34
34
n/a
Antec Signature 650
15
15
15
18
18
28
36
47
n/a
SilverStone DA700
18
18
18
18
23
32
35
41
n/a
Nexus RX-8500
14
14
17
22
28
32
32
33
33
NesteQ ECS7001
22
22
22
21
23
25
36
37
n/a
PCPC Silencer 610
20
24
24
24
24
30
40
50
n/a
The green boxes represent >30 dBA@1m SPL.
*Guesstimates based on the Modu82+ 425's idle in the chamber and the Modu82+ 625's load test.

Except at the 400W SPL, the Seasonic X-650 edges out or matches every other PSU. If the above table was converted to a line graph, the X-650 would have the smallest area under the line. Its closest competitors for low noise are the Nexus Value 430, Antec CP-850, Seasonic M12D-850 (and the untested 750W version of this model, presumably), Chill Innovation CP-700M and Enermax Modu82+ 625. However, when efficiency and overall electrical performance are also considered, only the Antec CP-850 and Seasonic M12D-850 are worthy competitors.

Caution: Please keep in mind that the data in the above table is specific to the conditions of our test setup. Change the cooling configuration, the ambient temperature and any number of other factors, and you could change the point at which the fans start speeding up, as well as the rate of the rise in speed. The baseline SPL is accurate, however, probably to within 1 dBA.



Previous 1 2 3 4 5 6 Next

Power - Article Index
Help support this site, buy the Seasonic X650 650W Power Supply from one of our affiliate retailers!