OCZ EliteXStream 1000 W Power Supply Review
By Gabriel Torres on November 13, 2008
OCZ EliteXStream 1000 W is one of the most affordable 1,000 W power supplies available on the market today. Its lower price point was achieved by carrying fewer features compared to other 1,000 W models, such as less auxiliary power cables for video cards (only four) and the absence of a modular cabling system. On the other hand OCZ was able to put this power supply inside a housing with a depth of only 6 19/64” (160 mm), while other 1,000 W models like Corsair HX1000W needs to use a bigger housing with a depth of 7 7/8” (20 cm). But is this a good power supply? Let’s see if it survives our load tests.
We were very curious to test this power supply, because we had already tested another 1,000 W model from OCZ, ProXStream 1000 W. We were not impressed by this other model from OCZ especially because it uses two printed circuit boards and two 80 mm fans, what made this other model to heat like hell, to be heavy and very noisy. The project from this other model was presented efficiency below 80% when we were pulling 800 W or more from it. With these two problems we simply can’t recommend ProXStream 1000 W.
Like ProXStream 1000 W, EliteXStream 1000 W also provides a small form factor like mentioned, but at least OCZ is using a 120 mm riffle bearing fan on its bottom instead of an 80 mm fan on its rear and another on its front. As you know, 120 mm or bigger fans on the bottom of the power supply is preferred as they provide a higher air flow and a lower noise level.
As you can see, this power supply does not have a modular cabling system, what helped to lower the manufacturing cost and thus the final price of the product.
It has “only” four auxiliary power cables for video cards, all using 6/8-pin connectors. We say “only” because competing 1,000 W models may offer six or more cables, which is desirable on 1,000 W units. Power supplies from this power range are clearly targeted to PCs with three or four video cards. Since very high-end video cards require two auxiliary power connectors with EliteXStream 1000 W you can only power two very high-end cards directly. If you want to have more than that you will need to use adapters to convert peripheral power plugs into video card power connectors.
EliteXStream 1000 W has four other cables for peripherals, one with four standard peripheral power connectors, one with four standard peripheral power connectors and one floppy disk drive power connector and two with four SATA power connectors each. The unit also has one EPS12V connector with no ATX12V support and the main 24-pin motherboard connector can’t be transformed into a 20-pin one. So you can only use this power supply with motherboards with an EPS12V connector.
On the aesthetic side all cables use a nylon sleeving that comes from inside the power supply housing.
On this power supply all peripheral wires are 18 AWG, with the +5 V and +3.3 V wires from the main motherboard cable being 16 AWG, which is really nice (i.e., they are thicker). It would be nice to see more 16 AWG wires on a 1,000 W product.
This power supply has active PFC, so it can be sold in Europe, and because of that it also features auto voltage selection. OCZ says this unit has 82% efficiency. Of course we will measure efficiency during our tests.
This power supply is really manufactured by Impervio. This manufacturer also produces power supplies for SilverStone. Even though the external appearance, internal layout and primary from OCZ EliteXStream 1000 W is identical to SilverStone OP1000-E, the secondaries from these two power supplies are completely different.
Now let’s take an in-depth look inside this power supply.
We decided to disassemble this power supply to see what it looks like inside, how it is designed, and what components are used. Please read our Anatomy of Switching Power Supplies tutorial to understand how a power supply works and to compare this power supply to others.
This page will be an overview, and then in the following pages we will discuss in detail the quality and ratings of the components used.
What immediately got our eye was the fact that this power supply had two transformers and three electrolytic capacitors on the active PFC circuit. We will see how they are connected in just a bit.
As we have mentioned in other articles and reviews, the first place we look when opening a power supply for a hint about its quality, is its filtering stage. The recommended components for this stage are two ferrite coils (the two coils with a black rubber protection on the pictures below), two ceramic capacitors (Y capacitors, usually blue), one metalized polyester capacitor (X capacitor, yellow component on the pictures below) and one MOV (Metal-Oxide Varistor, yellow component with black rubber protection in Figure 10). Very low-end power supplies use fewer components, usually removing the MOV and the first coil.
The transient filtering stage from this power supply is flawless. The big metallic piece that looks like an ordinary AC connector is in fact a complete line filter. This is the first time we’ve seen a PC power supply using such component. This power supply has one extra ferrite coil and two extra X capacitors but no Y capacitors. We wouldn’t worry about this for two reasons, first the presence of the line filter, which has these components inside, and secondly because after the rectification bridge this power supply has one more X capacitor and two Y capacitors.
In the next page we will have a more detailed discussion about the components used in the EliteXStream 1000 W.
On this page we will take an in-depth look at the primary stage of EliteXStream 1000 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.
This power supply uses one GBJ2006 rectifying bridge in its primary, capable of delivering up to 20 A at 110° C. This component is clearly overspec'ed: at 115 V this unit would be able to pull up to 2,300 W from the power grid; assuming 80% efficiency, the bridge would allow this unit to deliver up to 1,840 W without burning this component. Of course we are only talking about this component and the real limit will depend on all other components from the power supply.
click to enlarge
Figure 8: Rectifying bridge.
The active PFC circuit uses three 20N60C3 power MOSFET transistors, the same used by several other power supplies we looked. Each one is capable of handling up to 300 A @ 25° C in pulse mode (which is the case) or up to 45 A @ 25° C or 20 A @ 110° C (note the difference temperature makes). Usually the active PFC circuit has only two transistors. Other power supplies that use three transistors on the active PFC circuit we’ve seen so far include Zalman ZM-600HP, OCZ StealthXstream 600 W and OCZ GameXstream 700 W.
Another unusual thing about the active PFC circuit from this power supply is the use of three Japanese electrolytic capacitors from Hitachi rated at 105° C connected in parallel. When capacitors are connected in parallel the value of their capacitances are added. So three 330 µF capacitors connected in parallel is equivalent as one single 990 µF capacitor. This is a very smart trick to achieve a higher capacitance without using a physically bigger component. This is the best possible configuration: Japanese capacitors, high temperature range and very high capacitance.
On the switching section this power supply uses two other 20N60C3 transistors, on the traditional two-transistor forward configuration. The specs for these transistors are published above. They drive the two available transformers, which have their primaries connected in parallel. So even though this power supply has two transformers they share the same driving circuit.
As you can see in Figure 10, all main semiconductors from the primary side are installed on the same heatsink.
This power supply uses a discrete active PFC/PWM controller instead of using an integrated circuit that has this circuit already ready to use. On this power supply this circuit was built using one LM339 comparator, one UC3845B current mode controller and one ICE2PCS02 PFC controller.
On this power supply the first transformer and part of the second transformer are used to produce the +12 V outputs. The second transformer is also in charge of producing the +5 V and +3.3 V outputs.
This power supply uses synchronous topology for rectifying the +12 V output. On this topology the rectifying diodes are replaced by power MOSFET transistors. In theory this design offers a higher efficiency, as the voltage drop added by each transistor is of only 0.1 V or less, while a typical Schottky rectifier presents a voltage drop of 0.5 V. In other words, less conduction loss (wasted power) is introduced, thus increasing efficiency. The four power MOSFET transistors used for rectifying the +12 V output are FDP047AN08A0, which support a maximum current of up to 80 A at 144° C each and a far higher current at pulse mode, which is the case (we would need to know the frequency at which the switching transistors operate to make the proper calculation, so let's consider the maximum continuous current for our math below).
The maximum theoretical current the +12 V line can deliver is given by the formula I / (1 - D), where D is the duty cycle used and I is the maximum current supported by the rectifying diode (which in this case is made by two 80 A transistors in parallel). Just as an exercise, we can assume a typical duty cycle of 30%. This would give us a maximum theoretical current of 229 A or 2,743 W for the +12 V output. The maximum current this line can really deliver will depend on other components, in particular the coil used. As you can see the design used is clearly overspec'ed.
The +5 V output is produced by two STPS30L45CT Schottky rectifiers, each one capable of handling up to 30 A (15 A per internal diode) at 135° C. The maximum theoretical current the +5 V line can deliver is given by the formula I / (1 - D), where D is the duty cycle used and I is the maximum current supported by the rectifying diode (which in this case is made by two 15 A diodes in parallel). Just as an exercise, we can assume a typical duty cycle of 30%. This would give us a maximum theoretical current of 43 A or 214 W for the +5 V output. The maximum current this line can really deliver will depend on other components, in particular the coil used.
The +3.3 V output is produced by two STPS30L30CT Schottky rectifiers, each one capable of handling up to 30 A (15 A per internal diode) at 140° C. The maximum theoretical current the +3.3 V line can deliver is given by the formula I / (1 - D), where D is the duty cycle used and I is the maximum current supported by the rectifying diode (which in this case is made by two 15 A diodes in parallel). Just as an exercise, we can assume a typical duty cycle of 30%. This would give us a maximum theoretical current of 43 A or 141 W for the +3.3 V output. The maximum current this line can really deliver will depend on other components, in particular the coil used.
It is interesting to note that the +5 V and +3.3 V lines don’t share the same output from the transformer, as usually happens.
On the secondary heatsink we also found the rectifier for the +5VSB (“standby power”) output, a SBL1060CT. This device can handle up to 10 A (5 A per internal diode). This explains the higher current limit this power supply has for its +5VSB output (4 A) compared to other products (this is in fact the highest limit we’ve ever seen; most high-end power supplies can deliver up to 3 A or 3.5 A on the +5VSB output).
Another component found on the secondary heatsink is a voltage regulator integrated circuit for the -12 V output (LM7912). This device has a current limit of 1.5 A. The use of this integrated circuit explains why the -12 V output was so stable during our tests (usually manufacturers use cheaper solutions for the -12 V output, which results in a tremendous ripple on this output). We will talk more about this later.
The outputs are monitored by a PS232 integrated circuit, which supports the following protections: over current (OCP), under voltage (UVP) and over voltage (OVP). Any other protection that this unit may have is implemented outside this integrated circuit.
Talking about protections, notice how this power supply has two thermal sensors on the secondary heatsink. Usually this means that the product has over temperature protection (OTP), but there is no reference to this protection on OCZ’s website and since the montoring integrated circuit does not implement this protection we would need to analyze the circuit in more details to confirm this suspicion.
The electrolytic capacitors from the secondary are from Teapo, a Taiwanese company. It would be great if the manufacturer also used Japanese caps here.
In Figure 15, you can see the power supply label containing all the power specs.
This power supply uses a single rail design, so there is nothing to talk about here. It is interesting to note that internally the +12 V wires are divided into five groups (+12V1, +12V2, +12V3, +12V4 and +12V5) and using wires with different colors. So the manufacturer could have a product with five virtual rails if it implemented individual over current protection (OCP) to each set of wires.Now let’s see if this power supply can really deliver 1,000 W.
We conducted several tests with this power supply, as described in the article Hardware Secrets Power Supply Test Methodology.
We tested this power supply with five different load patterns, trying to pull around 20%, 40%, 60%, 80%, and 100% of its labeled maximum capacity (actual percentage used listed under “% Max Load”), watching how the reviewed unit behaved under each load. In the table below we list the load patterns we used and the results for each load.
If you add all the power listed for each test, you may find a different value than what is posted under “Total” below. Since each output can vary slightly (e.g., the +5 V output working at +5.10 V), the actual total amount of power being delivered is slightly different than the calculated value. On the “Total” row we are using the real amount of power being delivered, as measured by our load tester.
+12V1 and +12V2 are the two independent +12V inputs from our load tester and on this case they were connected to the same rail from the power supply, as OCZ EliteXStream 1000 W features a single rail design. The configuration below is exactly the same we used on our tests with other 1,000 W power supplies, like OCZ ProXStream 1000 W and Corsair HX1000W.
8 A (96 W)
14 A (168 W)
22 A (264 W)
30 A (360 W)
33 A (396 W)
8 A (96 W)
14 A (168 W)
22 A (264 W)
28 A (336 W)
33 A (396 W)
2 A (10 W)
6 A (30 W)
8 A (40 W)
10 A (50 W)
22.5 A (112.5 W)
2 A (6.6 W)
6 A (19.8 W)
8 A (40 W)
10 A (33 W)
22 A (72.6 W)
1 A (5 W)
2 A (10 W)
2 A (10 W)
3 A (15 W)
3.5 A (17.5 W)
0.5 A (6 W)
0.5 A (6 W)
0.5 A (6 W)
0.5 A (6 W)
0.5 A (6 W)
% Max Load
Ripple and Noise
AC Power (1)
|AC Power (2)||265.0 W||477.3 W||735.0 W||981.0 W||1,273.0 W|
|AC Voltage||109.2 V||109.6 V||104.1 V||101.1 V||96.8 V|
Updated 06/25/2009: We re-tested this power supply using our new GWInsteak GPM-8212 power meter, which is a precision instrument and provides accuracy of 0.2% and thus presenting the correct readings for AC power and efficiency (results marked as "2" on the table above; results marked as "1" were measured with our previous power meter from Brand Electronics, which isn't so precise as you can see). We also added the numbers for AC voltage during our tests, an important number as efficiency is directly proportional to AC voltage (the higher AC voltage is, the higher efficiency is). Also, manufacturers usually announce efficiency at 230 V, which usually inflates efficiency numbers. We added power factor (PF) numbers as well. These numbers measure the efficiency of the power supply active PFC circuit. This number should be as close to 1 as possible and the active PFC circuit from this unit is outstanding, as it was able to maintain power factor at 0.99 for all loads.
This power supply can really deliver 1,000 W at 50° C with an amazingly low noise level. Ripple and noise were always below 10 mV at +5 V outputs, where the maximum admissible value is 50 mV (peak-to-peak values)! Pulling 1,000 W from this power supply noise level on +12 V and +3.3 V outputs were not even half of the maximum admissible (which is 120 mV for the +12 V output and 50 mV for the +5 V output).
Voltages were very stable all the time, although +3.3 V and +5 V outputs dropped a little bit during test number five (power supply delivering 1,000 W), but still inside the 5% tolerance set by the ATX/EPS12V standard.
Even -12 V was incredible stable and with very low ripple. Usually the -12 V output oscillates like crazy, because manufacturers use cheap solutions for its rectification, filtering and regulation. Since this power supply used a voltage regulator integrated circuit to handle this output it achieve excellent results on this output. The maximum noise level we’ve seen for it was 13.8 mV when the power supply was delivering 1,000 W; on Corsair HX1000W, for example, noise level at -12 V was at 62 mV when it was delivering the same amount of power.
You will get a high efficiency with this power supply if you pull up to 60% of its labeled capacity (600 W): between 83.5% and 85%. With 80% load (800 W) efficiency dropped to 81.5%, still above 80%. But when we pulled around 1,000 W efficiency dropped below the 80% mark: 78.2%. This is not really a problem, as high-wattage power supplies are targeted to users that what to run them at half of their labeled capacity in order to achieve the best efficiency possible (click here to learn more about this question). You will never be able to pull anywhere close to 1,000 W with a personal computer.
Below you can see noise level when we were pulling 995 W (test number five) from this power supply. Just to remember, the maximum allowed for the +12 V outputs is 120 mV peak-to-peak and the maximum allowed for the +5 V and +3.3 V outputs is 50 mV peak-to-peak.
Unfortunately we couldn’t test if this power supply could deliver more than 1,000 W due to a limitation in our equipment. On test number five (1,000 W) we were already pulling the maximum amount of current our equipment is capable of pulling from its two +12 V inputs (33 A or 396 W each). Thus we couldn’t pull more than 1,000 W the way we wanted. Of course we could keep the +12 V inputs at 33 A and increase current at +5 V and +3.3 V, but that is not the configuration we wanted, as we always want to pull as much as we can from the +12 V outputs from the power supply, as today that is where consumption is concentrated (video cards and CPUs are fed by the power supply +12 V outputs through the video card auxiliary cables and EPS12V/ATX12V, respectively).
For the same reason we couldn’t test the power supply over current protection (OCP), since EliteXStream 1000 W +12 V rail has a limit of 80 A but we could pull only 66 A.
EliteXStream 1000 W power supply specs include:
* Researched at Shopping.com on the day we published this review.
We were really impressed by OCZ EliteXStream 1000 W. It can really deliver 1,000 W at 50° C with one of the lowest ripple and electrical noise levels we’ve ever seen. You will get a high efficiency with this power supply if you pull up to 60% of its labeled capacity (600 W): between 83.5% and 85%. With 80% load (800 W) efficiency dropped to 81.5%, still above 80%. But when we pulled around 1,000 W efficiency dropped below the 80% mark: 78.2%. This is not really a problem, as high-wattage power supplies are targeted to users that what to run them at half of their labeled capacity in order to achieve the best efficiency possible (click here to learn more about this question). You will never be able to pull anywhere close to 1,000 W with a personal computer.
This is a good product, especially when you compare it to the previous 1,000 W unit from OCZ, the ProXStream, which has a lousy efficiency (79% when you pull 800 W, only 74.5% when delivering 1,000 W), a small and noisy fan and a very serious heating problem due to its excess of components squeezed into a very small form factor combined with an inefficient fan.
ProXStream costs less, but please stay away from it. EliteXStream is a little bit more expensive but is worth every extra penny. In fact, it is cheaper than other 1,000 W models like Corsair HX1000W and Thermaltake Toughpower 1000 W.
Of course there must be a trade-off for its lower price and this can be found on the lack of a modular cabling system and a reduced number of power cables for video cards.
The presence of only four video card cables is the main drawback from this product (even though all of them use 6/8-pin connectors, which is an advantage), because it limits you from installing more than two very high-end video cards with two auxiliary connectors each without the use of adapters, and we believe that most people looking for a 1,000 W product will have more than two video cards. Of course you can use adapters on the peripheral power plugs to get the extra connectors you will need.
If this limitation doesn’t bother you, go ahead and buy OCZ EliteXStream 1000 W: it is one of the 1,000 W power supplies with the best cost/benefit on the market today.