Test Setup

All measurements are performed utilizing ten electronic loads (seven Array 3711A, 300W each, and three Array 3710A, 150W each), which are able to deliver over 2500W of load and are controlled by a custom made software. We also use a Picoscope 3424 oscilloscope, a CHY 502 thermometer, a Fluke 175 multimeter and an Instek GPM-8212 power meter. Furthermore, in our setup we have included a wooden box, which along with a heating element is used as a Hot Box. Finally, we have at our disposal four more oscilloscopes (Rigol 1052E and VS5042, Stingray DS1M12 and a second Picoscope 3424) and a CEM DT-8852 sound level meter. In this article you will find more details about our equipment and the review methodology we follow. Finally, if the manufacturer states that the maximum operating temperature of the test unit is only 40°C then we try to stay near this temperature, otherwise we crank up the heat inside the hotbox up to 45-50°C.

Voltage Regulation Charts

The following charts show the voltage values of the main rails, recorded over a range from 60W to the maximum specified load, and the deviation (in percent) for the same load range.

5VSB Regulation Chart

The following chart shows how the 5VSB rail deals with the load we throw at it.

Efficiency Chart

In this chart you will find the efficiency of TPX-1275M at low loads and at loads equal to 20-100% of PSU's maximum rated load.

Voltage Regulation and Efficiency Measurements

The first set of tests reveals the stability of voltage rails and the efficiency of TPX-1275M. The applied load equals to (approximately) 20%, 40%, 50%, 60%, 80% and 100%, of the maximum load that the PSU can handle. In addition, we conduct two more tests. In the first we stress the two minor rails (5V & 3.3V) with a high load, while the load at +12V is only 2A and in the second test we dial the maximum load that +12V can handle while load at minor rails is minimal.

Apparently the high-end technology used in this unit works as far as efficiency is concerned. At 40% of max rated load efficiency peaks at an impressive 93% and even at full load and with very high operating temperature it's above 91%. Only at 20% load it's a little low, for platinum standards of course since it's still close to 90%.
Voltage regulation overall is loose, especially at +12V. Unfortunately this is the price a PSU has to pay in order to achieve the highest possible efficiency. From the other high power Platinum units only the Seasonic Platinum 1000W so far avoided the loose voltage regulation curse.
Fan noise was very low. Until the last minute of test #2 and despite the relatively high ambient temperature the fan didn't spin at all. Afterwards it operated at low-medium RPMs, even when we applied full load, so it was very quiet and fairly effective judging from the temperature delta difference at 100% load and CL2 tests.
Here we should note that in our first tests the fan didn't spin, even with full load at >40°C ambient. So we opened the PSU to determine the cause. As it seems the thermistor responsible for fan speed control, didn't make good contact with one of the two main transformers so the internal temperature had to reach inferno levels before the control circuit activated the fan. Since the unit we had in our hands was not new/sealed and apparently it was opened, probably from another reviewer, we can't be sure if this a generic or an isolated problem (we will ask of course for a second unit to test).
What also troubled us was that the fan's operation is only temperature dependent and doesn't take into account the load applied to the PSU at a current time. We would prefer a hybrid method since this way the PSU's internal components are heavily stressed and also without OTP present things can get really nasty.

Efficiency at Low Loads

In the next tests, we measure the efficiency of TPX-1275M at loads much lower than 20% of its maximum rated load (the lowest load that the 80 Plus Standard measures). The loads that we dial are 40, 60, 80 and 100W (for PSUs with over 500W capacity). This is important for scenarios in which a typical office PC is in idle with power saving turned on.

If you want good efficiency at such low loads then better look elsewhere, at lower capacity PSUs. Who ever buys a 1275W beast most likely will never operate it at such low loads. These units are intended for three/four way SLI, Crossfire systems so it is a shame to have them power an entry level PC.

5VSB Efficiency

ATX spec states that the 5VSB standby supply's efficiency should be as high as possible and recommends 50% or higher efficiency with 100mA load, 60% or higher with 250mA load and 70% or higher with 1A or more load.
We will take four measurements, three at 100 / 250 / 1000 mA and one with the full load that 5VSB rail can handle.

The 5VSB rail boasted quite high efficiency reaching 80% with full load. Overall good performance here.

Power Consumption in Idle & Standby

In the table below you will find the power consumption and the voltage values of all rails (except -12V), when the PSU is in idle mode (On but without any load at its rails) and the power consumption when the PSU is in standby (without any load at 5VSB).

Vampire power is dead low at only 0.1W. It is fascinating to see a beast like this draw only one tenth of the ErP Lot 6 2010 limit, in standby mode.