Reviews - XFX Pro Series 1250W Black Edition
Sample Provided by: XFX (By jonny on Mon, Jan-23-2012)

Page 3 - Load test results

I use a SunMoon SM-8800 load tester to put artificial loads on power supplies. Different cables plug into different connectors on the front of the load tester and each connector is assigned a load.

With a single +12V rail power supply, I usually don't pay too much mind to what plugs in where. I typically just plug in as many connectors as possible into the front of my load tester and fire it up. But for this power supply, I couldn't do a full load and was wondering if the power supply was really a 1250W or if it was tripping off because of the high temperatures. I even ran my tests at room temperature and the power supply still shut down.

XFX ensured me that the power supply should do 1250W without issue and sent me a second unit. I plugged the second unit into the load tester and experienced the same problem. At high loads, the power supply kept shutting down.

So what's the deal? Well, it turns out that EasyRail isn't EasyRail after all. This power supply actually has four +12V rails. The way I hooked up the cables to the power supply, and the way the +12V is distributed was causing the OCP to trip. I was plugging the 4+4-pin into my load tester and the 4+4-pin shares a +12V rail with the 24-pin connector; so putting a load on both of these connectors was putting the total load on one +12V rail.

After some emails and trial and error (like, a whole day of trial and error), it turns out the DC output table should look something like this:

XFX Pro
1250W

+3.3V

+5V

+12V1

+12V2
+12V3
+12V4

12V

+5VSB

25A

25A

30A

30A
45A
45A

0.5A

3A

Max Power

150W

1248W

6W

15W

1250W

Now, will this be a problem for someone installing this power supply in a real computer? Well, the most you'd probably ever load up the CPU power connector is around 20A. The most you're going to send through the 24-pin connector's +12V wires is around 10A. The likelihood that you're going to send that much power through both of the connectors all at once is next to nil.

Below is our cable listing again, this time showing what +12V rail goes to what connector:

XFX Pro 1250W

Type of connector:

Quantity:

+12V Rail
Modular Cables

24-pin ATX connector (600mm)

1

+12V1

8-pin ATX12V/EPS12V (700mm)

1

+12V4

8-pin (4+ 4-pin) ATX12V/EPS12V (700mm)

2

+12V1

6+2-pin PCIe (4 cables w/ 2 connectors each) (600mm)

8

+12V2 or +12V3

SATA (3 cables w/ 3 connectors each) (550mm+150mm+150mm)

9

+12V4

SATA (1 cables w/ 2 connectors) (360mm+170mm)

9

+12V4

5.25" Peripheral Power Connector (2 cables w/ 3 connectors each) (450mm+150mm+150mm+150mm)

6

+12V4

5.25" Peripheral Power Connector (1 cables w/ 2 connectors) (360mm+170mm)

2

+12V4

3.5" Drive power adapter (Splitter that adds two +170mm cables to the end of 5.25" Peripheral Power Connector)

2

+12V4

Unit Dimensions(L x W x H)

190mm x 86mm x 150mm

Now that we got that all figured out, I unplugged the 4+4-pin power connector and used the 8-pin CPU power connector and plugged it into the +12V4 connector that can be used for either an 8-pin CPU power connector or PCIe cable.

The +12V load on my load tester is split up across six different connectors.  Each connector gives me a different voltage, though.  Because the differences are largely because of resistance in the connectors and/or wires, I log the highest voltage reading in my table.  That said, if you "do the math", you might find total wattage numbers lower than "they should be" because ALL voltage readings are taken into account when total wattage is calculated.

Finally, these tests are performed in a 19°C room, but the hot air from the load tester is pumped into the intake of the power supply in an effort to emulate actual operating temperatures, so as the load increases the temperature of the power supply increases just as it would in your PC.

XFX Pro 1250W HOT load tests

Test #

+3.3V

+5V

+12V

+5VSB

DC Watts/
AC Watts

Eff.

Power
Factor

Intake/
Exhaust

Simulated system load tests

Test
0

0A

0A

0A

1.5A

7.6W/
9.8W

77.6%

.54

19°C/
19°C

     

5.07V

Test
1

1.8A

1.8A

8.5A

1.5A

124.4W/
150.1W
82.9%
.98
23°C/
25°C

3.33V

5.04V

12.02V

5.04V

Test
2

3.6A

3.6A

17.7A

1.5A

249.8W/
282.1W

88.6%

.98

27°C/
30°C

3.33V

5.04V

12.03V

5.05V

Test
3

5.4A

5.4A

26.9A

1.5A

375.2W/
417.8W

89.8%

.99

30°C/
34°C

3.33V

5.04V

12.03V

5.04V

Test
4

7.2A

7.2A

36.0A

1.5A

498.7W/
553.3W

90.1%

.99

34°C/
40°C

3.32V

5.04V

12.03V

5.02V

Test
5

9.0A

9.0A

45.2A

1.5A

623.5W/
689W

90.5%

.99

36°C/
42°C

3.32V

5.01V

12.03V

5.00V

Test
6

10.8A

10.8A

54.4A

1.5A

747.9W/
836W

89.5%

.99

41°C/
45°C

3.32V

5.03V

12.03V

4.99V

Test
7

14.5A

14.5A

72.7A

1.5A

995.5W/
1132W

87.9%

.99

44°C/
50°C

3.31V

5.03V

12.03V

4.92V

Test
8

18.1A

18.1A

91A

1.5A

1238.5W/
1472W

84.1%

.99

46°C/
58°C

3.29V

5.01V

12.02V

4.88V

Test
CL1

0A

0A

104A

0A

1239W/
1445W

85.7%

.99

47°C/
59°C

3.31V

5.03V

12.07V

4.95V

Test
CL2

18.1A

18.1A

2A

0A

175.1W/
216.1W

81%

.99

42°C/
45°C

3.32V

5.04V

12.01V

5.09V

Low and behold, the power supply stopped shutting down, even when exhaust temperatures hit 59°C.

The first observation I take away from these results is how well the voltage sense circuitry works on this unit. +3.3V only dropped .04V. +5V dropped a mere .03V and the +12V actually went up .01V before coming back down to +12.02 where we started.

Voltages also stayed well within specification when crossloaded.

Efficiency looks very good on this unit. Test 2, 5 and 8 are 20%, 50% and 100% loads respectively. 88.6%, 90.5% and 84.1% efficiencies at these loads means this unit comes very close to 80 Plus Silver status. There's an 80 Plus Gold logo on the box, but with full load efficiency of 84.1% this unit is pretty far off from the 87% efficiency required to get an 80 Plus Gold certification. I would re-test the unit using the 80 Plus Gold loads from the test report on their website, but there is no 1250W power supply on the list of XFX power supplies certified by 80 Plus. Of course, we already know that this power supply is based off the Seasonic X-Series 1250W, so we can use the test settings for that unit to see if we can hit 80 Plus Gold.

XFX Pro 1250W 80 Plus load tests

Test #

+3.3V

+5V

-12V

+12V

+5VSB

DC Watts/
AC Watts

Eff.

Simulated system load tests

20%

3.2A

3.2A

0.1A

18.4A

0.5A

251.1W/
282.3W
88.9%

3.33V

5.04V

-11.73V

12.03V

5.08V

50%

7.9A

7.9A

0.2A

45.9A

1.3A

624.3W/
692W

90.2%

3.32V

5.04V

-11.88V

12.02V

5.01V

100%

15.8A

15.8A

0.4A

91.7A

2.6A

1241.7W/
1449W

85.7%

3.31V

5.03V

-12.24V

12.02V

4.90V

Using the loads the 80 Plus folks used to test the Seasonic X-Series 1250W, we did a little better at 100% load, but we're still not at 80 Plus Gold efficiency.

Now let's have a look at the ripple:

Oscilloscope Measurements for XFX Pro 1250W
Test #
+3.3V
+5V
+12V
+5VSB
Test 1
Test 2
Test 3
Test 4
Test 5
Test 6
Test 7
Test 8
Test 9 (CL 1)
Test 10 (CL2)

The ripple is a little wavy on the +12V rail, and downright choppy at full load, but it's well within specification.

Now we're going to look for overshoot transients and rise time on the +5VSB by going from full off to full load on the +5VSB, and on the +12V by going from standby to full load on the +12V and full off to full load on the +12V.

Overshoot Transient Testing for XFX Pro 1250W
Off to VSB On
VSB to Full, 12V
Off to Full, 12V

So we can see here that rise time is about 10ms on both the +5VSB and +12V and there's virtually no overshoot whatsoever.

Now let's bust out the screwdriver and take this power supply apart.



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