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Enthusiast Power Protection: Four-Way 900 W UPS Roundup
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1. Power Protection Or Rage Prevention?

Few events are more upsetting than getting to the toughest part of a game and having your PC go down. Less traumatic (but still troublesome) are situations like losing a video only seconds before you’re done re-encoding it. Even losing a carefully-written email before it can be sent is enough to push some Tom's Hardware editors past the edge of sanity (Ed.: *raises hand*).

Enthusiasts often rely on little more than a surge protector to keep their hardware safe. But these devices can’t prevent brownouts from resetting a computer, nor can they prevent blackouts from stopping the computer in its tracks completely. The inevitable result is lost work, even when that “work” is an entertainment-oriented task.

While mainstream users have long been able to buy low-cost uninterruptable power supplies, the unique demands of enthusiast-class hardware have often put this type of protection out of reach.

A quick look at the specifications recommended by four top UPS manufacturers for our enthusiast build could help to explain the enormous price disparity. 

Enthusiast UPS Features
 APC Smart-UPS
SMT1500
CyberPower
CP1500PFCLCD
Opti-UPS Durable
DS1500B
Tripp Lite SmartPro
SMART1500SLT
TopologyLine-InteractiveLine-InteractiveDouble-ConversionLine-Interactive
Wave FormPure SineAdaptive SinePure SinePure Sine
Wattage980 W900 W1050 W900 W
VA Rating1440 VA1500 VA1500 VA1500 VA
UPS OutletsEightFiveSixEight
Surge OnlyNoneFiveNoneNone
Power GroupsTwo (4+4 Jacks)OneTwo (4+2 Jacks)One
Dimensions17.3" x6.7" x8.6"14.4" x4.0" x10.5"17.0" x6.0" x9.4"13.3" x6.7" x10.2"
Weight52.5 Pounds24.8 Pounds38.4 Pounds44.5 Pounds
Web Price $442  $191  $548  $338


Notice that all of the units in today’s review produce something that approximates a true sine wave, something that costs far more to produce than the stepped square waves of lower-cost parts. We’ll explain why this is so important on our next page, before going into the individual characteristics that make each model special.

2. Why So Pricey?

Most of our enthusiast-class builds have an approximate value of $2000. Because a $200 UPS represents only 10% of the system’s price, we thought a roundup of those would bolster our “cheap protection” argument. That’s when the realities of modern hardware slapped us in the face.

Problem 1: Real vs. Apparent Power

Have you ever wondered why a UPS of enormous VA rating might be required to support a far more moderate wattage load? Aren’t watts calculated by multiplying volts by amps, the V and A in VA ratings? Getting to the bottom of this required us to think about a few of the things we learned in high-school science classes and apply those lessons to a Web search.

The AC (alternating current) power that comes from our wall jacks is graphically represented as a sine wave, where the center line is equal to ground. Voltage is rated using RMS values, so a 120 V line is 170 V peak (RMS * √2). In a perfect world, current (amperage) would track force (voltage) perfectly, resulting in a peak wattage (at the crest of the wave) that’s far higher than the average wattage for a single cycle. That is to say, even in a perfect world, the circuit must be designed to handle more than its rated power.

Unfortunately, amperage load doesn’t always track voltage perfectly, and this is where VA and watts part ways. When voltage and amperage are slightly out of phase, a portion of the energy from the load (such as a computer’s power supply) returns to the source (such as a UPS battery). Though the cancelled-out power reduces the energy required from the source, all the parts between the source and the load must be beefed-up to carry it.

VA ratings are a way for power supply companies to advertise the current-carrying capacity of those middle parts without discussing the continuous load the battery is able to supply to the PC.

Problem 2: Active PFC and Step Waves

While traditional PC power supplies focus on reducing electrical noise on the output rails, Power Factor Correction-equipped power supplies also attempt to reduce the noise the unit places on its power source. Filters align amperage and voltage cycles, reducing the portion of energy that is returned from the load to the source. That is to say, a power supply with perfect PFC (1.0) would never require the middle parts to carry more VA than the PC consumes in watts. With enthusiast PC power supplies now advertising 0.95-0.99 PFC, it’s time most of us learned to ignore VA ratings and focus on the wattage capacity of our UPS devices.

Yet active PFC power supplies can also be more sensitive to wave form than traditional PC power supplies have been. Dan Farnsworth of APC explains:

“For some basic info, Europe has required that all electronics devices now be made with PFC power supplies for a while now. And they are becoming more common here in the US as time passes. These power supplies are more efficient...but also more expensive. Accordingly, in order to minimize cost increases associated with active PFC power supplies, some manufacturers are cutting corners in their power supply designs, which can impact the compatibility of traditional desktop (modified square wave output) UPSs with computer systems that use these new power supplies. For example, in some cases, the PFCs' "hold up" time is shorter, meaning UPSs, which normally would work fine with a computer, now do not transfer to battery power fast enough to keep the computer running during an outage. Active PFC power supplies can also draw excessively large inrush currents upon initial operation or during switches to battery power, overloading a UPS that would otherwise have been properly sized. Some active PFC power supplies work better when they receive pure sine wave power (Smart-UPS units), rather than the "modified sine wave" output of a Back-UPS unit, although, our testing shows that some active PFC power supplies don't care which type of output they receive.”

The problem is graphically represented at the CyberPower Systems Web site as a zero-output state occurring as a step-wave crosses from positive to negative voltage. While that zero-output state persists only for milliseconds, that’s still far longer than the instant that it occurs on a true sine wave. For most UPS manufacturers, the option is to upsell their customers a true-sine-wave model that costs far more to produce.

CyberPower’s solution appears to clip the peaks on a triangular wave, eliminating the zero-output state at lower cost than pure sine wave equipment. CyberPower calls this its “adaptive sine wave” technology, and one of our goals is to test its capabilities using a mid-priced, “enthusiast market,” active PFC power supply.

3. APC Smart-UPS SMT1500

The heaviest unit in today’s roundup, APC’s Smart-UPS SMT1500 is designed to keep power-hungry systems running for extended periods from its high-capacity batteries. A removable front panel allows easy access to a hot-pluggable battery tray, allowing failing batteries to be replaced without shutting down attached equipment.

If you’re beginning to think that the SMT1500 sounds like a commercial unit that’s been designed for mission-critical applications, you’re right. This design may seem overkill for any level of home PC. But the reality is that enthusiast-class PC hardware has become overkill by traditional UPS standards. A combination of true sine wave circuitry and super-high wattage output has pushed the SMT1500’s internal hardware cost beyond the typical home PC market, and hot-replaceable batteries are expected in commercial applications.

Front-panel controls make it possible to configure the SMT1500’s added features without software, while an LED display lets users know exactly what changes they’re about to make.

Load shedding is made possible by the SMT1500’s division of power across two groups, where Group 1 can be set to shut down long before the main power group. We’d normally plug peripherals into these connectors.

The Smart-UPS SMT1500 includes documentation on both paper and CD, USB and nine-pin serial cables, and management software.

4. SMT1500 Management Software

Windows 7 users can rejoice in that they don’t actually need any additional software to shut down their PC when battery power is low. That’s because simply connecting a USB cable between the PC and UPS allows the OS to read battery level, enabling user control of CPU power state, sleep and suspend modes, low-level and critical-level actions in the same way they would a notebook. Additional functions can be controlled from the SMT1500 front panel, but those who want to load the software will find a wider range of utilities.

APC PowerChute Web-based utility spreads the unit’s main statistics across four pages that require a password for access.

Line-interactive uninterruptable power supplies switch between battery and input power depending on input voltage. APC allows the users to define how sensitive that switching function should be. A narrower range of voltages offers increased system stability, while a broader range provides increased battery life. Automated diagnostics scheduling assures users that they’ll know far in advance before the battery needs replacement.

Load shedding is available on one bank of power connections, allowing users to determine how soon they’d like power-wasting peripherals to be shut down separately from the PC.

Additional power controls allow users to determine how much reserve power they’d like, and how quickly a shut-down system should power back up.

The SMT1500 can be set to notify users via email about monitoring errors, power events, etc. That’s handy when you’re away from the PC and need someone to tend to it.

Logging functions are rather convoluted, yet some users would rather have access to more features rather than fewer.

5. CyberPower CP1500PFCLCD

The long name for CyberPower’s upper-mainstream backup unit is easily broken down into brand (CP), VA rating (1500), PFC power supply support, and an LCD front-panel display.

Besides being the smallest, lightest, and cheapest unit in today’s roundup, the CP1500PFCLCD is also the only unit that has not fully replaced step-wave with pure-sine-wave circuitry, instead opting for a modified triangular wave that CyberPower calls “Adaptive Sinewave” to eliminate the zero power state that has so often prevented step-wave units from working with active PFC power supplies. This basically means that users get the enhanced compatibility of a sine wave unit at a low price similar to many step wave competitors.

A large LCD panel eases manual configuration from the unit itself, giving users one more excuse not to install the included management software. Enhanced front-panel capabilities also make the CP1500PFCLCD a better choice for non-PC power backup applications, such as home theater system protection, and CyberPower even lets you charge your USB-equipped cell phone from the front panel. If you’re starting to think this might be the perfect device for household emergencies, that’s probably the kind of thinking CyberPower is hoping to foster.

Unlike more expensive solutions that have configurable load-shedding outlets, the CP1500PFCLCD has five battery-backed and five surge-only outlets (two covered by the red warning label). PC users can plug unneeded peripherals like their speakers and printer to the surge-only connections for instant power-off, preserving the battery for their PC and monitor. Similarly, home-theater users can keep required devices, such as their TV, cable box, and radio plugged into the battery-backed side as they listen to emergency alerts, while unnecessary devices power off instantly to preserve the unit's limited battery life.

CyberPower surprised us by including a telephone and TV cables in its installation kit, along with the expected USB cable, manual, and software CD.

6. CP1500PFCLCD Management Software

Windows 7 users can configure power settings for their desktop PC as they would a notebook once the USB cable is connected, but some may still be interested in the added features found in CyberLink’s software suite.

The name PowerPanel Personal Edition provides additional proof that this model is designed for end-users rather than commercial applications, and gives us hope that simplified menus will aid end-users in accessing the device's advanced features.

While Windows already allows users to schedule power-on and power-off for the PC, setting these on the UPS allows peripheral power to be cut as well.

Users can also designate reserve power or battery runtime using PowerPanel software, though we prefer to do this through the default utilities built-into Windows 7.

Line-Interactive power supplies only switch to battery power when input voltage crosses a certain threshold. Increasing that threshold allows the CP1500PFCLCD to rely upon the battery less, extending battery life, while reducing that threshold can increase system stability.

Users who want to use something other than default settings but don’t know what numbers to punch in can instead select from various sensitivity profiles on the next menu.

The CPS1500PFCLCD includes a self-test function to keep track of battery condition.

7. Opti-UPS Durable Series DS1500B

Opti-UPS might be considered a high-value brand in the traditional consumer market, but none of its consumer products were ready to support active PFC power supplies. Stepping up to server-grade parts, it still had to go upscale to support the high loads of an enthusiast-class PC. The DS1500B is so upscale, it’s the only unit it today’s comparison to use double-conversion topology.

Double-conversion means that 100% of the output power comes directly from the batteries, while the input side is isolated from the output side through the batteries. Two completely separate power circuits are required to make this all work, but the chief benefit is that a double-conversion unit can tolerate far greater input power fluctuations without impacting stability on the output side. Because the outputs run continuously from the battery, there is no need to switch between power sources, and the batteries themselves become part of the voltage and current buffer.

A simplified front panel is less verbose than that of some competitors, but a little patience still allows users to “get the job done” without relying on software. Of course, those who don’t have much patience can just as easily install the control software to access advanced functions.

Besides having the highest capacity of today’s competitors at 1050 W, the DS1500B is also able to have the longest run time through the addition of external battery packs. On the other hand, the added cost of a double-conversion power unit means that many end users won’t have enough money left to purchase external batteries.

Two power groups allow users to configure load shedding, turning off unneeded peripherals to conserve battery life.

We were very surprised to find that the DS1500B does not include a USB cable, since very few modern systems have retained the nine-pin serial interface. The older interface is still common on servers however, and that’s the primary market for this high-end unit.

8. DS1500B Management Software

The DS1500B’s software CD does not support any modern operating system, but available updates do. Windows 7 users are of course welcome to use the operating system’s native UPS support, which gives desktop PCs the power options previously reserved for notebooks.

Opti-UPS' Opti-Safe software appeals to us in that its simplified interface provides most of the functionality found in competing, complicated solutions. The monitoring and power-failure configuration menus exemplify its ease-of-use.

The scheduling menu and event recording menus are also simplified, reminding us of programs from the Windows for Workgroups era. We were particularly fond of the record viewer, which is as easy to use as the video player apps of the 1990s.

Opti-Safe can even call for help, but only via serial port modems. Modern hardware users will have to make due with email notification. Email notifications on smart phones are an option as well.

9. Tripp Lite SmartPro SMART1500SLT

Short, fat, and heavy, Tripp Lite’s SMART1500SLT attempts to overcome the price barriers of its APC rival through selective reductions in features. Customers retain enterprise-class features like a hot-swap battery tray and pure sine wave output, but lose the convenient LED front-panel display.

Also gone is the load shedding feature, which Tripp Lite addresses through separately-purchased power bars. All eight outlets belong to a single power group.

The SMART1500SLT’s simplified design also means that more users will want to use its included software suite, which can be accessed by either USB or nine-pin serial connections.

Tripp Lite includes documentation, USB and legacy serial cables, and a software CD in its SMART1500SLT support kit.

10. SMART1500SLT Management Software

As with other UPS devices, Windows 7 users also have the option of configuring their desktop’s power and shutdown settings using OS-based controls identical to those of notebook PCs. Those who need advanced features will find a friendly interface in Tripp Lite’s PowerAlert Agent Console.

Status menus show basic statistics of line voltage, load level, and battery state.

The SMART1500SLT is able to network Tripp Lite’s special power bars to enable load shedding, but doesn’t support it internally. Users can, however, configure how and when the UPS initializes system shutdown.

11. Test Settings
Hardware Configuration
CPUIntel Core i7-950 (3.06 GHz, 8 MB Shared L3 Cache)
O/C to 4.35 GHz (23 x 189 MHz), 1.40 V
MotherboardGigabyte X58A-UD3R, BIOS FB (08/24/2010)
Intel X58 Express / ICH10R
RAMMushkin Enhanced 998586 (6 GB), DDR3-1333 at DDR3-1134 CAS 8-8-8-21
Graphics2 x EVGA 012-P3-1470-AR 1.25 GB, SLI
O/C at 700 MHz GPU, GDDR5-3404
Hard Drive2 x A-Data AS599S-64GM-C 64GB SSD, Striped, MLC, SATA 3Gb/s
SoundIntegrated HD Audio
NetworkIntegrated Gigabit Networking
PowerSilverStone ST85F-P 850 W Modular
ATX12V v2.3, EPS12V, 80 PLUS Silver, Active PFC
Software Configuration
OSMicrosoft Windows 7 Ultimate x64
GraphicsNvidia Graphics Driver Version 260.99
ChipsetIntel INF 9.1.2.1007
Benchmark Configuration
CPU LoadPrime95 v25.8. 64-bit executable, Small FFTs,  Eight Threads
GPU LoadFurMark 1.6.5 Stability Test, 1920x1200, 4x AA
Combined LoadPrime95 (Seven CPU Threads) plus FurMark (One CPU Thread)


Assembled for an upcoming overclocking article, our test system pulls 407 W under Prime95, 676W under FurMark, and 870W with both programs running at full force. FurMark requires one dedicated CPU thread to reach full GPU load.

Less-aggressive overclockers can get similar power consumption at far lower clock speeds using higher-cost hardware, such as Intel’s Core i7-980X processor and a pair of Nvidia’s GeForce GTX 580 graphics cards.

12. Benchmark Results

An ideal comparison might show run time versus cost using UPS devices with similar features, but competing feature sets makes that type of comparison impossible. Features often cost more than upsized batteries, so run time is only a single component of today’s multi-faceted test.

Lead-acid batteries are super-reliable and super-heavy, so it makes sense that our runtime chart is a reflection of unit weight. But how do these compare in power protection?

Opti-UPS provided the only UPS with double-conversion topology, which means that all of the unit's output power is filtered through the batteries first. That technique produces superior protection against surges and brown-outs, but at higher cost. The results of line-interactive units are a reflection of their default sensitivity settings, where user-adjustable increased sensitivity could reduce battery life.

Converting 100% of line-input power to battery power, then converting it back to line-output power is a somewhat inefficient process. The double-conversion unit from Opti-UPS thus falls to the bottom of the power consumption chart, which is probably a small sacrifice in exchange for the unit's improved protection.

CyberPower and APC use thermally-controlled fans, never getting hot enough to kick up to high speed even when placed under the extreme loads of an enthusiast-class PC. Either of these units is sufficiently quiet for use in an office environment, where they’d normally be placed at least twice the standard one-meter listening distance from the user.

Tripp Lite’s noise resembles that of a white-noise generator, which is soothing to some people. We’d still recommend placing it at least four meters from your chair.

The Opti-UPS DS1500B’s cooling fan runs at full-speed, full time, just like Tripp Lite's. Its higher noise likely reflects the higher heat generated by its more protective double-conversion design, yet the pitch of its noise is such that we’d reserve this unit for a server closet.

CyberPower exhibits amazing power efficiency, consuming around 1% more energy than the unprotected system. Opti-UPS’ double-conversion design requires more power to provide more protection.

13. Conclusion

Much love goes into building an enthusiast-class PC, and nothing could ruin that relationship quicker than bad power. While most of us get by with nothing more than a surge protector, many of us would be just as upset if a brownout reset our systems in the middle of a game or any other important task.

Yet, the UPS industry isn’t as nimble as the computer component industry, and was caught ill-prepared for changes in hardware that have been occurring over the past few years. While CyberPower is the first company to launch a consumer-level UPS to support enthusiast-class hardware, there’s a lot to be said in favor of its enterprise-class rivals. Let’s consider a few things each particular UPS is good at:

Best Power Protection: Opti-UPS DS1500B

If all of our PCs were stashed away in server closets, the UPS DS1500B could be the best choice to protect them. Double-conversion topology does an almost perfect job of isolating a PC from fluctuations in the power grid, making this the best solution for ultra-sensitive components. Unfortunately, it’s far too noisy for an office or den, and far too expensive to suite the budgets of typical $2000 PC owners. This is, after all, an enthusiast-market comparison.

Best Run Time Value: APC SMT1500

The second-most-expensive unit in today’s roundup was also the second quietest and the one to provide the most battery run time for the money:

Even though its long runtime allows APC’s SMT1500 to top our value chart, most enthusiasts are unlikely to pay $442 to protect their $2000 system. Our preference for the SMT1500 is strong enough that if pricing was not an issue, APC would be getting an award.

Best Enthusiast Value: CyberPower CP1500PFCLCD

Priced around ½ that of the competing average, CyberPower’s CP1500PFCLCD is the only unit in today’s comparison designed specifically for high-end home users. Consequently, it’s the only unit cheap enough to appeal across the broader enthusiast market, and the only unit to qualify for our “Recommended Buy” award within that market. Added features are simply icing on the cake, since it’s the only unit to pass the market’s price sensitivities, in addition to our durability tests.

Quiet enough to go nearly anywhere in the home, an easy-to-use front panel controller even makes it suitable for backing-up less elaborate devices like home theater equipment, perfect for keeping broadcast news updates available during a storm.

A scant runtime is this model’s biggest downfall compared to enterprise-class rivals, yet enthusiasts are also more likely to finish their tasks within the several minutes of full-load power the unit provides. We told every manufacturer that this article would be a value UPS shootout for the enthusiast PC market, and that’s exactly where the CP1500PFCLCD excels.