DC Load Regulation and AC Ripple
Establishing an accurate load is critical to testing and evaluating a PC power supply. PCPerspective’s power supply test bench can place a precise DC load on the PSU under test. Each power supply is tested under controlled, demanding conditions up to its maximum rated load (at 40ºC). Our current suite of tests includes:
• DC Load Regulation
• AC Ripple and Noise
• Differential Temperature
The SilverStone SX700-LPT power supply was evaluated on both features and performance. A full range of equipment was used to test the power supply under controlled load conditions.
• (2) CSI3710A Programmable DC load (+3.3V and +5V outputs)
• (4) CSI3711A Programmable DC load (+12V1, +12V2, +12V3, and +12V4)
• (2) 200W Precision resistor load bank (+12V5 and +12V6)
• Switchable precision resistor load bank (-12V and +5VSB)
• Agilent 34401A digital multimeter (Accuracy ±0.0035% vDC)
• Extech 380803 Power Analyzer (Accuracy ±0.5% of full scale)
• DS1M12 "StingRay" digital oscilloscope (20M S/s with 12 Bit ADC)
• Extech Model 407738 digital sound level meter (Accuracy ±1.5 dB)
The following cables/connectors were used to connect the power supply to the PCPerspective power supply test equipment.
• (1) 20+4 pin ATX
• (1) 8-pin EPS/ATX12V
• (4) 6-pin PCI-E
• (2) SATA
• (2) Molex
DC Output Load Regulation
To simulate demanding and maximum loading conditions, the SX700-LPT power supply was connected to the load testers and supplied with a constant 120 VAC. In this test we are interested in seeing how well a PSU can maintain the various output voltages while operating under different loads.
The ATX12V V2.2 tolerance for voltages states how much each output (rail) is allowed to fluctuate and has tighter tolerances now for the +12V outputs. We have included a second table of expanded tolerances (±1% to ±6%) for reference.
The following tables list the DC voltage results for the SilverStone SX700-LPT PSU while operating on 120 VAC, 60 Hz.
The power supply produced very good voltage regulation on all of the DC outputs with the three main rails staying within ±2% of the recommended ATX guidelines; even better than SilverStone’s claim of ±3%.
AC Ripple and Noise on the DC Outputs
The amount of AC ripple and noise present on the DC outputs was checked using a digital oscilloscope. This AC component may be present in the KHz range where most switching power supplies operate or it may be more prevalent at the 60 Hz line frequency. We adjust the O-scope time base to look for AC ripple at both low and high frequencies. The ATX12V V2.2 specification for DC output noise/ripple is defined in the ATX12V Power Supply Design Guide.
Ideally we would like to see no AC ripple (repetitive) or noise (random) on the DC outputs – the cleaner the better! But in reality there will always be some present. I measured the amplitude of the AC signal (in millivolts, peak-to-peak) to see how well the power supply complied with the ATX standard. The following table lists the ripple/noise results during all of the load tests for the main output voltages of interest.
Overall the SX700-LPT power supply exhibited very good AC ripple and noise suppression with the results staying well below the ATX recommended guidelines, even at full load. The AC ripple suppression on the +3.3V and +5V outputs was excellent while the +12V output showed a little more activity at high loads.
SFX-L seems like such a
SFX-L seems like such a pointless standard, you can get SFX PSUs at 600W, no small system is gonna pull more power than that.
First off, they clearly laid
First off, they clearly laid out the advantages of having a 120mm fan for lower noise.
You also lack imagination. SFX and SFX-L now make ATX sized units seem ridiculously big and unnecessary. Silverstone is coming out with a 800W 80+ Titanium rated SFX-L unit later on this year that could power an overclocked HEDT processor and dual Titan X rig easily (a lot of people over estimate the power needs for a system by a lot).
I have an R9 Nano in an SFF
I have an R9 Nano in an SFF build which has a recommended PSU of 750W.
I bought this PSU for that build. It does just fine, even when the GPU and CPU (which is a 6600K) are both overclocked.
The 450W PSU which I had with the case originally wasn’t enough for the GPU at peak load, let alone with a 95W TDP CPU + overclock. It had two 12V rails. This has one 12V rail with 58A. More than enough.
There’s nothing wrong with meeting the recommended specs *and* having some additional headroom.
i will be running 2x gtx 1080
i will be running 2x gtx 1080 hybrids off one of these with a i7-6700k all overclocked using every drop of power this thing has to offer
A gem of a review once again.
A gem of a review once again. Why did Silverstone only put a 3 year warranty on this? That makes no sense. It should indeed have at least an 5 year warranty.
I would advise caution when
I would advise caution when buying this PSU do to quality control. I bought one off Amazon for my ITX build, but the PSU would randomly shut off as if the power cord was unplugged. This would happen at random times like while installing Windows, watching Youtube, or just idling. I would have to unplug the power cord from the PSU to be able to restart my PC.
I returned it and bought the SX500-LG and so far it has worked perfectly.
I’m not saying you’re wrong.
I’m not saying you’re wrong. I’m just saying that one faulty OCP circuit does not indicate a QC problem, it indicates one faulty OCP circuit.
There’s a lot of that
There’s a lot of that happening, people are complaining on forums and reviews on neweeg.ca points that same issue, which is very sad. To be fair my corsair sf600 is having the same issues,It has to do with power surges.
There is a bug with the
There is a bug with the semi-fanless mode on the SX700-LPT: The fanless mode is triggered by dropping below a certain power draw only, rather than by power and/or temperature. But the unit still has overtemp protection. This means if the unit is heated up while under low-load conditions, it can become warm enough to trigger overtemp shutdown without the fan ever kicking in!
Whether this is an issue depends on PSU orientation (opening-down = bad), inlet restriction (e.g. fan filters), case airflow (if any), and ambient temperature.