Why you can trust Tom's Hardware Our expert reviewers spend hours testing and comparing products and services so you can choose the best for you. Find out more about how we test.
Advanced Transient Response Tests
For details about our transient response testing, please click here.
In the real world, power supplies are always working with loads that change. It's of immense importance, then, for the PSU to keep its rails within the ATX specification's defined ranges. The smaller the deviations, the more stable your PC will be, with less stress applied to its components.
We should note that the ATX spec requires capacitive loading during the transient rests, but in our methodology, we also choose to apply a worst case scenario with no additional capacitance on the rails.
Advanced Transient Response at 20% – 20ms
Advanced Transient Response at 20% – 10ms
Advanced Transient Response at 20% – 1ms
Advanced Transient Response at 50% – 20ms
Advanced Transient Response at 50% – 10ms
Advanced Transient Response at 50% – 1ms
Results 25-29: Transient Response
Transient response is satisfactory at 12V and excellent at 5V and 5VSB. At 3.3V, the deviations are not high, but we would like to see over 3.2V the moment the transient load is applied, in all cases.
Turn-On Transient Tests
In the next set of tests, we measured the PSU's response in simpler transient load scenarios—during its power-on phase. Ideally, we don't want to see any voltage overshoots or spikes since those put a lot of stress on the DC-DC converters of installed components.
Turn-On Transient Response Scope Shots
There are no major voltage-overshoots or spikes in the Thermaltake ToughPower TF1 1,550W's turn-on transient tests, so all is well here.
Power Supply Timing Tests
A power supply generates several signals, all of which need to be within specified ranges as laid out by the ATX spec. If they are not, there can be compatibility issues with other system parts, especially mainboards. From 2020 on, the PSU's Power-on time (T1) has to be lower than 150ms and the PWR_OK delay (T3) has to be from 100 to 150ms, to be compatible with the Alternative Sleep Mode.
|T1 (Power-on time) & T3 (PWR_OK delay)|
This PSU's PWR_OK delay slightly exceeds the upper PWR_OK delay limit with 20% load, while it is right on it with full load. We believe this is a pass, given our equipment's margin of error.
Ripple represents the AC fluctuations (periodic) and noise (random) found in the PSU's DC rails. This phenomenon significantly decreases the capacitors' lifespan because it causes them to run hotter. A 10-degree Celsius increase can cut into a cap's useful life by 50%. Ripple also plays an important role in overall system stability, especially when overclocking is involved.
The ripple limits, according to the ATX specification, are 120mV (+12V) and 50mV (5V, 3.3V, and 5VSB).
|10% Load||11.7 mV||6.4 mV||11.0 mV||4.0 mV||Pass|
|20% Load||15.0 mV||6.7 mV||23.1 mV||4.2 mV||Pass|
|30% Load||18.9 mV||6.5 mV||11.4 mV||4.6 mV||Pass|
|40% Load||15.4 mV||6.7 mV||11.4 mV||4.3 mV||Pass|
|50% Load||14.5 mV||8.1 mV||11.9 mV||4.7 mV||Pass|
|60% Load||17.1 mV||7.5 mV||12.7 mV||5.1 mV||Pass|
|70% Load||15.3 mV||7.8 mV||13.4 mV||5.2 mV||Pass|
|80% Load||15.9 mV||7.7 mV||18.9 mV||4.9 mV||Pass|
|90% Load||16.3 mV||8.2 mV||13.5 mV||5.8 mV||Pass|
|100% Load||21.2 mV||8.6 mV||14.5 mV||6.0 mV||Pass|
|110% Load||22.3 mV||8.3 mV||14.8 mV||5.8 mV||Pass|
|Crossload 1||13.3 mV||7.4 mV||12.9 mV||4.6 mV||Pass|
|Crossload 2||22.0 mV||8.7 mV||14.5 mV||5.7 mV||Pass|
Results 30-33: Ripple Suppression
Ripple suppression is great on all rails, especially if we consider this PSU's max power.
Ripple At Full Load
Ripple Full Load Scope Shots
Ripple At 110% Load
Ripple 110% Load Scope Shots
Ripple At Cross-Load 1
Ripple CL1 Load Scope Shots
Ripple At Cross-Load 2
Ripple CL2 Load Scope Shots
EMC Pre-Compliance Testing – Average & Quasi-Peak EMI Detector Results
Electromagnetic Compatibility (EMC) is the ability of a device to operate properly in its environment without disrupting the proper operation of other nearby devices.
Electromagnetic Interference (EMI) stands for the electromagnetic energy a device emits, and it can cause problems in other nearby devices if too high. For example, it can be the cause of increased static noise in your headphones or/and speakers.
We measured this PSU's EMI with 53W and 200W loads, and in both case we noticed several high spurs exceeding the corresponding limits.
MORE: Best Power Supplies
MORE: All Power Supply Content
Current page: Transient Response Tests, Timing Tests, Ripple Measurements and EMC Pre-Compliance TestingPrev Page Protection Features, DC Power Sequencing, Cross-Load Tests and Infrared Images Next Page Performance, Noise, Efficiency and Power Factor
Aris Mpitziopoulos is a Contributing Editor at Tom's Hardware US, covering PSUs.