Hot Test Results

As we can see from their performance tables, the ST30SF and the ST45SF both display very good power quality figures for PSUs of their class. The filtering figures of the ST30SF are better, with a maximum ripple of about 42 mV on the 12V line under maximum load. The ST45SF reached up to 64 mV on the 12V line under maximum load, but that was to be expected given its much higher output. If we were to compare the two units on a per-watt basis, the ST45SF does deliver better power quality figures, which is to be expected considering its more capable electronic components. The voltage regulation of both units is almost identical, with an average of about 1.7% on the 3.3V/5V lines and 1.9% on the 12V line.

SilverStone ST30SF Main Output
Load (Watts) 60.95 W 151.64 W 226.57 W 299.92 W
Load (Percent) 20.32% 50.55% 75.52% 99.97%
  Amperes Volts Amperes Volts Amperes Volts Amperes Volts
3.3 V 1.31 3.37 3.28 3.35 4.91 3.33 6.55 3.32
5 V 1.31 5.1 3.28 5.08 4.91 5.05 6.55 5.03
12 V 4.09 12.19 10.23 12.12 15.35 12.08 20.47 11.98


Line Regulation
(20% to 100% load)
Voltage Ripple (mV)
20% Load 50% Load 75% Load 100% Load CL1
3.3V + 5V
3.3V 1.6% 12 10 10 12 10 12
5V 1.5% 8 12 12 16 10 12
12V 1.8% 14 24 28 42 38 20

Even though SilverStone rates the new revision models at 40 °C, they had no problem reaching their maximum power output inside our hotbox. Unexpectedly, their energy conversion efficiency dropped only very slightly as well, with the average nominal load (20-100%) efficiency dropping down to 85.6% and 85.8% for the ST30SF and the ST45SF respectively. We would expect the impact to be much higher considering their design and the very high temperatures, but both units proved us wrong. 

SilverStone ST45SF Main Output
Load (Watts) 91.65 W 228.35 W 338.28 W 449.76 W
Load (Percent) 20.37% 50.74% 75.17% 99.95%
  Amperes Volts Amperes Volts Amperes Volts Amperes Volts
3.3 V 1.69 3.38 4.22 3.37 6.33 3.32 8.44 3.31
5 V 1.69 5.12 4.22 5.09 6.33 5.06 8.44 5.03
12 V 6.33 12.21 15.83 12.17 23.75 12.01 31.66 11.99


Line Regulation
(20% to 100% load)
Voltage Ripple (mV)
20% Load 50% Load 75% Load 100% Load CL1
3.3V + 5V
3.3V 1.65% 16 16 18 18 16 16
5V 1.7% 18 20 20 22 24 20
12V 1.9% 18 26 36 64 68 40


Power Losses

The low impact of the high temperature on the efficiency of the units hints that the active components of both units are significantly oversized for their design and power rating and could, in theory, sustain their power output with an ambient temperature of 50 °C. The operating temperatures however are very high, with the ST30SF reaching temperatures of nearly 92 °C under maximum load and the ST45SF a few degrees higher than that. 

Intake & Exhaust Air Temperature

Heatsink Temperature

Under such operating conditions we can see that the fans of both units shoot up to their maximum speed before the units even reach 50% of their rated maximum power output. The ST45SF reached a maximum sound pressure level of about 56 dB(A), higher than the 52 dB(A) of the ST30SF, due to its more powerful fan. The more powerful fan proved to be more than a necessity, as the ST45SF can barely maintain nominal operating temperatures when heavily loaded. 

Sound Pressure Level
Cold Test Results Final Words & Conclusion


View All Comments

  • wolfemane - Thursday, January 26, 2017 - link

    We are at a good point in power consumption where 550w and up aren't needed for standard builds. I'm running an i5-6600k oc'ed to 4.5ghz paired with a gtx 1080 on an asus mitx pro gaming board. M.2 os drive, couple mid range ssds for storage, and your basic 16gb ddr4-3200. At the wall, under load I'm barely drawing 400w. Currently using the 450w that comes with the Node 202. Reply
  • takeship - Friday, January 27, 2017 - link

    Second to this. I purchased one of these Silverstone 450's a whopping 3y ago (v2 at the time) for a mITX Haswell i5 build with a GTX 660 (ncase m1). At load the system never topped 350w (according to HWMonitor), but it was more than enough (esp with the 80cm fan) and left a good bit of room to upgrade to something newer in the future. 8pin PCIe connectors are amazing for future proofing. Reply
  • takeship - Friday, January 27, 2017 - link

    Still running without issue as well, for whatever the data value of my own anecdote is. Reply
  • NZLion - Tuesday, January 31, 2017 - link

    The system I have running on a 600W SFX PSU is an ITX box with i7 6850K, 32GB DDR4 3000, Titan X Pascal, and 2TB Samsung 960 Pro M.2
    I haven't measured the load at the wall, but according to an online calculator (Outervision) I am likely using about 520W
  • zodiacfml - Friday, January 27, 2017 - link

    300W is plenty these days. Thanks for the review. I am interested in such PSUs. I miss building PCs again, but now, I want the challenge of compact ones. Reply
  • Zan Lynx - Sunday, January 29, 2017 - link

    That entirely depends on what you are building. A top end Intel CPU at full load can burn 140W plus the motherboard at 30W. Add a high end GPU at full load for 250W and you're at 420W already. Spinning hard drives idle at about 5W but during power-up they use up to 35W to spin up. There's been many a home-server builder with a broken build because their 8 drive system didn't have enough watts. NVMe SSDs use a lot of power during writes, the Intel models use up to 30W. Reply
  • Ascaris - Saturday, January 28, 2017 - link

    I considered PSU reviews very carefully before I bought my current one. I find them extremely useful! Reply
  • thomasg - Sunday, January 29, 2017 - link

    I, too, do appreciate such reviews, as they are actually useful for me a lot of times.
    Others should consider, that they might me more useful to them than they think, because more often than not such PSUs are much more suitable to most builds than the high-end stuff people seem to think they want.

    There clearly is a need for good low-powered PSUs for smaller builds, and there really is a heavy lack of such units.
    Just 2 weeks ago a friend asked me for a recommendation for a small media-server build for a couple of hard-disks in a small case, and I really had a hard time recommending anything with a practical power envelope.

    It's really absurd that people think the widely available oversized PSUs are ever useful, as there is only a tiny tiny fraction of builds that can utilize them to more than 50% load.
    A 600W PSU in a small SFX case seems ridiculous, as it is extremely unlikely that anyone will be using a >100W CPU and more than one 300W GPUs in those.
    In this high-end setup even with reserves and some hard-disks you won't ever utilize more than 500W on the 12V rails. A 600W PSU will typically provide at least 550W on the 12V rails.

    My rule of thumb for builds is to reach 80% load on 12V for hardware you're actually going to use, and if possible 20% load at typical low-power use (achieving 20% on idle would be ideal, but is impractical).
    My dated Phenom II X6 setup is using a 550W GPU.
    This is the X6 running at 4 GHz with slight voltage increase (max. 150W), a HD7970 (max. 300W), Chipset 15W, Storage 30W, 3 180mm fans (15W). Combined max. 510W.
    Considering some of the power draw is not on the 12V rails, a PSU with 550W on 12V is plenty with some reserves.
    This is an old platform with very high-draw components, that just aren't typical anymore.

    So let's see what we can do with a 300W SFX PSU (obviously this will be no ultra-high-end overclocking system, that's simply not the purpose):
    i5 65W, GTX 1070 150W, SSD+2*2,5" disks 20W, Chipset+RAM+Controllers 30W = 265W.
    The 300W PSU can handle this easily with reserves.

    Anyway, thanks for the review, I'm sure I will take these units into consideration for upcoming builds.
  • none12345 - Monday, January 30, 2017 - link

    I wouldnt load a 450 watt power supply with 400 watt, 90% load will havea pretty short service life. Assuming you game a lot. Personally i shoot for ~80% load on electronics, it seems to make them last a hell of a lot longer. As well as power supplies being more efficient at ~80% load then ~90%.

    If i knew i would have a 400 watt load when gaming i would buy either a 500, or 550 watt, depending on price/specs. a 650 is too big, a 450 is too small in my opinion. You already have an approiately sized ps for that load.
  • thomasg - Wednesday, February 1, 2017 - link

    As I said, 80% is the number to go for, we're not disagreeing.
    However, I'd argue, that you shouldn't be too conservative with your reserves, as actual usage will almost always be lower than the theoretical maximum.
    Even with games using your hardware to the fullest extent, you won't ever draw maximum power for the components.
    Your CPU will never draw maximum current outside of specifically designed synthetic benchmarks. Neither will your GPU. If you get to full load in a real world scenario it will unlikely last for more than a second at a time.

    As this review shows, a reasonable quality PSU will handle even 100% load over a extended period of time without too much efficiency loss, so no reason to be overly cautious.
    Gaming will practically never get you to continuous maximum power usage of your main components.

    That said, different usage demands different configurations, so if you're building a render node, feel free to oversize a little.

    Just don't overdo it. Pick the suiting hardware for the job, just as you do with other components. Oversizing too much will cost you doubly.

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