Test results and thoughts
Each of the five power supplies under consideration has a different power rating, so it's difficult to make like-for-like comparisons.
Even so, the tests we carry out are highly illuminating, especially when the PSUs are seen in the light of their widely differing price-tickets.
Far and away the most expensive of the bunch is the Enermax Galaxy 1000W. It costs around £224.
We'll pause here for a moment, to let that sink in.
Number two - and at some distance - is its 850W stablemate, priced about £165. And that ticket for the "cheap" Enermax model also merits a little pause for consideration, we feel.
Next down is the SilverStone Zeus 850W at £152. The other two PSUs are somewhat less expensive - but hardly cheap.
The Tagan 800W costs roughly £114 and the SilverStone Zeus 750W is £115. In present company, those prices are almost bargains but we struggle to see it that way.
Readings under load |
Power & efficiency |
||||||||||||||
PSU |
| +12V1 |
+12V2 |
+12V3 |
+12V4 |
+12V5 |
+5V |
+3.3V |
-12V |
+5VSB |
Input power |
Ideal output |
Actual output |
Efficiency |
|
Enermax Galaxy 850W |
Voltage |
11.975 |
11.95222 |
11.975 |
11.975 |
11.9 |
4.782 |
3.268 |
-12.152 |
4.95 |
1011 |
851.6 |
846.19 |
83.7% |
|
Current |
14 |
14 |
17 |
11 |
6 |
12 |
12 |
0.25 |
1 |
||||||
Enermax Galaxy 1000W |
Voltage |
11.865 |
11.77 |
11.88 |
11.865 |
11.737 |
4.775 |
3.167 |
-12.212 |
4.932 |
1227 |
1021.4 |
1000.87 |
81.6% |
|
Current |
14 |
17 |
17 |
11 |
13 |
18 |
18 |
0.25 |
1 |
||||||
SilverStone Zeus 750W |
Voltage |
11.79 |
11.782 |
11.81 |
11.837 |
N/A |
4.93 |
3.27 |
-12.127 |
4.972 |
912 |
749 |
737.36 |
80.9% |
|
Current |
13 |
13 |
14 |
14 |
N/A |
12 |
10 |
0.25 |
1 |
||||||
SilverStone Zeus 850W |
Voltage |
11.78 |
11.785 |
11.78 |
11.84 |
N/A |
4.957 |
3.272 |
-12.202 |
4.952 |
1053 |
863.6 |
849.93 |
80.7% |
|
Current |
16 |
15 |
16 |
16 |
N/A |
12 |
12 |
0.25 |
1 |
||||||
Tagan Dual Engine 800W |
Voltage |
11.895 |
11.89 |
12.047 |
12.027 |
N/A |
4.93 |
3.317 |
-12.87 |
4.915 |
991 |
800.3 |
797.88 |
80.5% |
|
Current |
14 |
14 |
15 |
15 |
N/A |
12 |
11 |
0.25 |
1 |
||||||
For efficiency, the 850W Enermax Galaxy came up trumps, with close to 84% - a little ahead of the kilowatt version's 81.6%.
[advert]Pleasingly, all the supplies managed over 80% efficiency in our bench testing.
Hats off to the products on test; they manage to provide what their specifications suggest.
Temperature testing
| PSU | Ambient (°C) | PSU idle (°C) | PSU after load testing (°C) | Calculated delta (load - idle) (°C) |
|---|---|---|---|---|
| Enermax Galaxy 850W | 20 | 22.5 | 38 | 15.5 |
| Enermax Galaxy 1000W | 22 | 23 | 41 | 18 |
| SilverStone Zeus 750W | 20.5 | 20.5 | 58 | 37.5 |
| SilverStone Zeus 850W | 20.5 | 20.5 | 84 | 53.5 |
| Tagan Dual Engine 800W | 20.5 | 20.5 | 32.5 | 12 |
Other than a two-degree bump while we were testing the Enermax Galaxy 1000W, we were lucky enough to have a stable room temperature for the duration of our tests.
As you can see, while they were running idle, both Enermax supplies were slightly warmer than the ambient temperature. In contrast, the other PSUs remained at room temperature during their idle phases.
But you probably shouldn't read much into this discrepancy - it may have been due to our having attached the probes to the wrong kind of surface on the Enermaxs during this particular phase.
One thing we would like to highlight, however, is that the grilles of the SilverStone PSUs are designed such that when we attempt to get exhaust temperatures from them - in the way we do all PSUs - we seem to get higher readings. That's most likely because the thermometer is able to read internal component temperature rather than the temperature at the exhaust point.
Under full load, each of the twin-fan Enermax supplies stayed surprisingly cool, thanks to a large intake fan that forces cooling air swiftly through the housing.
The Tagan Dual Engine 800W managed the same feat and, at 32.5 deg C, was the coolest unit in our test. This excellent result was at the expense of noise, though.
As the Tagan loads up, its twin fans start to whine loudly. The high-pitched shrieking was, we judge, considerably louder than the 26dBA suggested by the marketing literature. But, at least the screaming was accompanied by ample cooling.
The 750W SilverStone reached a hefty temperature under load but the 850W model - at 85C under heavy load - made it's brother look like a refrigerator. But, as we've just said, we have concerns whether the way that we take readings may be the cause for these particularly high readings.