It’s been a while since we last reviewed a power supply—so long that our last review samples are now fully fossilized, waiting to be recovered by future generations of geologists. The factories where they were built now manufacture flying cars, and the term “PSU” itself is now a portmanteau for an extremely vulgar dance move.
Well, all right. Maybe not quite. But it has been a while.
There’s a very good reason for our moving away from PSU reviews, of course. Five to 10 years ago, finding a quiet and efficient PSU with enough 12V amps to power a real gaming rig was tricky. It involved careful comparison shopping and the perusing of many reviews, including our own. Without appropriate research, there was a very good chance of winding up with a noisy unit and an inadequate connector load-out. Today, though, 80 Plus-certified units with near-silent fans practically grow on trees. Most of the good ones have overly beefy 12V rails, five-year warranties, and more connectors than people need. And they’re modular, too.
The stakes, in other words, are much lower.
That said, we are curious types here at TR. We couldn’t resist the urge to look in on some recent PSUs, if only to verify what we’ve known for some time. Some itches simply have to be scratched. Especially the ones resulting from the aforementioned dance move.
To scratch this particular itch, we gathered semi-modular 750W units with 80 Plus Gold certification from Cooler Master and Rosewill—including a representative of Cooler Master’s newly released VSM series—and stacked them up against a member of the old guard, PC Power & Cooling’s Silencer 760W, which came out almost four years ago. Let’s see how far we’ve come over the past several years.
Cooler Master’s V750
We’ll introduce Cooler Master’s V750 first, since it’s the newest unit of the bunch.
Like many high-efficiency PSUs, the V750 derives most of its capacity from a single 12V rail. This rail is rated for 62A, which works out to 744W, or about 99.2% of the total output rating. That’s a good thing: the 12V line feeds the most power-hungry components in a system, including the CPU and GPU. The other rails aren’t nearly as important.
The V750 follows the current trend in other ways. It features a 120-mm fan (with dynamic speed adjustment), active power-factor correction, Japanese capacitors throughout, and a lofty efficiency rating. The 80 Plus Gold label on this thing denotes efficiency of 87-90% depending on the load, or 88-92% if you’re connected to a 230V AC outlet.
This is also a “semi modular” unit. The motherboard and PCIe power leads are hard-wired, but the others can be added or removed at the user’s discretion. We like modular and semi-modular designs, and we recommend them exclusively in our System Guide, because they make for much tidier builds with fewer airflow obstructions. With non-modular units, one has to find room to tuck away all the unused cables.
The V750 ships with four PCIe 6+2-pin connectors, so it can drive up to two top-of-the-line graphics cards with dual 8-pin power jacks. On top of that, the modular cables in the box provide eight Serial ATA connectors, six 4-pin Molex connectors, and one 4-pin floppy connector, for those still rocking old-school 1.44MB drives.
At 5.9″ x 5.5″ x 3.4″ (150 x 140 x 86 mm), the V750 is fairly compact. It’s actually about 0.9″ (23 mm) shorter than the Rosewill Capstone and about 1.6″ (40 mm) shorter than the Silencer. That smaller footprint corresponds exactly to the official ATX specification, but it’s uncommon among enthusiast-grade power supplies these days. Unlike the Capstone, Silencer, and a whole wealth of other units, the V750 will happily fit in Mini-ITX and microATX cases that support only standard-length PSUs.
This PSU will set you back $99.99, or $89.99 after a mail-in rebate, at Newegg. Cooler Master covers it with a five-year warranty and a “Gold Guarantee” that includes “live help” tech support and full coverage of replacement fees, such as shipping costs. That certainly doesn’t hurt.
On paper, the Capstone isn’t all that different from the V750. Active PFC, Japanese capacitors, dynamic fan control, and 80 Plus Gold certification are all part of the program. The Capstone even has the same 62A capacity on its lone 12V rail.
There are a few notable differences between the two units, though.
For starters, as we mentioned, the Capstone is about nine tenths of an inch longer, at 6.4″. As a result, it won’t fit in quite as many enclosures as the V750. The Capstone does put that extra bulk to good use, though, with a larger, 140-mm fan. That larger fan could translate into lower noise levels, since it should be able to dissipate the same amount of heat as the V750’s 120-mm spinner with fewer rotations per minute.
The Capstone also has a slightly different connector arrangement. While the motherboard leads are hard-wired, the PCIe ones are not. (You still get four 6+2-pin connectors.) Rosewill unit provides five 4-pin Molex connectors instead of six—which is worth noting if you have auxiliary fan controllers and stacks of old hard drives—and its cables aren’t quite the same length as the V750’s. More on cable lengths in just a minute.
For now, we’ll note that the Capstone-750-M sells for a little more than the V750, at $109.99. Rosewill does cover this unit with a seven-year warranty, though, which is two years longer than Cooler Master’s coverage. Seven-year warranties are more typically found on high-end units from companies like Corsair, so it’s nice to see Rosewill offering the same perk.
Before we get into more serious testing, let’s quickly compare the cable lengths of our power supplies. Nobody wants a PSU with needlessly short cables, especially when building a PC inside an extra-tall enclosure.
Here are the figures for the most critical connector types: motherboard, auxiliary 12V, PCIe, Serial ATA, and 4-pin Molex. In all cases, we measured the length from the body of the power supply to the end of the connector. We measured the distance to the last connector for the Serial ATA and Molex leads, since drives and fans can be connected individually with multiple leads; but we measured up to the first and last connectors for the PCIe leads, since many graphics cards require two power connectors in the same location. (The Silencer 760W has a single PCIe connector per lead, so that last part doesn’t apply to it.)
|Motherboard||59.0 cm||59.5 cm||51.0 cm|
|Auxiliary 12V||65.5 cm||64.0 cm||62.0 cm|
|PCIe (first plug)||55.4 cm||48.0 cm||61.0 cm|
|PCIe (last plug)||65.0 cm||59.0 cm||N/A|
|SATA (last plug)||86.5 cm||88.0 cm||105.5 cm|
|Molex (last plug)||74.0 cm||74.5 cm||106 cm|
|PCIe (first plug)||21.8″||18.9″||24.0″|
|PCIe (last plug)||25.6″||23.2″||N/A|
|SATA (last plug)||34.1″||34.6″||41.5″|
|Molex (last plug)||29.1″||29.3″||41.7″|
The V750 and Capstone are roughly comparable—except when it comes to the PCIe leads, which are weirdly short on the Capstone. They’re so short, actually, that I’m not sure you could comfortably route them behind the motherboard tray in larger ATX mid-tower cases. We’ll chalk up one point for Cooler Master here.
Our old-school reference unit, the Silencer 760W, has the longest PCIe and SATA leads by a longshot. That would be good if the PSU were modular, but it’s not. Having extra slack in hard-wired leads typically makes cable management more difficult.
For our first genuine test, we’ll look at the power efficiency of these units.
In the past, we’ve relied on some very sophisticated equipment to measure PSU efficiency. This time, we kept things simple—partly because of time constraints, and partly because there’s something to be said for a practical approach to this type of thing. Instead of subjecting our PSUs to an artificial load, we hooked them up to a real PC and checked the power draw for different workloads at the wall.
The PC we used for load testing featured a Phenom II 975 Black Edition processor, a Radeon HD 7970 graphics card, 8GB of RAM, one SSD, and two 7,200-RPM hard drives. The processor is a little out of date, but we chose the chip for its 125W TDP, which is about as high as desktop CPUs go these days. (For reference, Intel’s Core i7-4790K is rated for just 88W.) The Radeon HD 7970 has a 250W power envelope, which ain’t small. All told, the system drew upwards of 350W when running our load test.
That load test comprised a one-two punch of Prime95’s large-FFT torture test and Unigine’s Valley benchmark running with maxed-out detail levels. We let the system idle for five minutes, then we fired up Prime95 and Unigine Valley in rapid succession, and we let the hardware chew on that for another five minutes. Power draw was measured at the wall and logged using a Watts Up? Pro meter, which took one reading every second.
Here are the results of our test expressed as a line graph:
And here are the median power consumption numbers from the idle and load portions of the test:
Well, pop open the champagne and sound off your vuvuzelas. Cooler Master has just scored another point.
The V750 is the most efficient of the bunch, by a small margin, in both workloads. The Rosewill unit comes fairly close, while the Silencer 760W straggles behind both of its rivals. The Silencer’s poor performance here is no accident, since it’s only rated for 80 Plus Silver, meaning efficiency in the 85-88% range (or 85-89% with 230V AC input).
Now, the differences you see above only amount to a few watts, but they can add up. Let’s assume you never turn off your PC, and it idles 20 hours a day, every day. Let’s also assume your power company bills at 12 cents per kilowatt-hour. For just that idling time, you’d be looking at a $10 difference in yearly running cost between the V750 and the old Silencer. Multiply that by, say, five years, which is a reasonable amount of time to keep a power supply, and the efficiency disparity will have cost you 50 bucks. The difference between the Cooler Master and Rosewill units would be less—about $28.45—but that’s still a sizable surcharge over the cost of the PSU itself.
Efficiency matters, folks.
While running the 10-minute test above, we logged voltages using AIDA64. We then worked a little rudimentary Excel magic to extract the minimum and maximum recorded figures for each voltage rail. The resulting data tells us how consistent voltages were throughout our test procedure:
Yeah, voltage consistency really isn’t an issue with any of these PSUs. The Silencer 760W had the steadiest voltages of the bunch, while the V750 exhibited the most variation, but the differences were minuscule—certainly not enough to jeopardize stability or anything of the sort.
Last, but not least, we measured noise levels during our idle and load tests. We took readings from about 10 inches away, using a TES 52 sound level meter positioned strategically out of the path of airflow. Keep in mind these are results from an open test bench, so CPU and GPU fan noise are part of the picture.
The V750 and Capstone are about equally quiet. That’s true both according to our decibel meter and according to my own, human ears, which could barely make out any PSU fan noise over the system’s hum.
The Silencer 760W was another story, though. As you can see in the graphs above, it literally drowned out the noise from the rest of the system. That’s no surprise, though, since it’s a less efficient unit outfitted with a smaller, 80-mm fan. The Silencer has more heat to dissipate at any given load, and it must spin its fan faster to dissipate that heat.
So, what has this little courtesy visit to the PSU market taught us?
Well, it’s taught us that modern units can perform a fair bit better than even a high-end model from just a few years ago. (According to Camelegg, the Silencer 760W sold for about $145 back in 2011.) If you’re holding on to a PSU from the cretaceous period, you might want to consider an upgrade. Old PSUs may work well enough, but there’s a lot to be said for higher efficiency and near-silent operation.
As for the contest between Cooler Master’s V750 and Rosewill’s Capstone-750-M, the outcome is, I think, fairly clear. The V750 has a lower asking price, higher power efficiency, longer PCIe cables, and dimensions compatible with smaller enclosures that don’t support extra-long power supplies. It’s slightly louder than the Capstone under load, but the difference, to my ears, isn’t noticeable—and the V750 is quieter at idle. All in all, we think the V750 has earned a TR Recommended award.
None of that is to say the Capstone isn’t a worthwhile purchase. While it’s larger and a little less efficient than the V750, and its PCIe leads are a little short, the Capstone is effectively equivalent to the V750 in most other respects. It has a longer, seven-year warranty, too, which may very well justify its small price premium.