OCZ 780W ModXstream PSU Page: 1
The humble power supply unit (PSU) is an item of hardware that is often overlooked when specifying a new PC. Generic PSU's are often shipped in 'pre-built' PC's that while fine for the average user (if you consider low efficiency and poor reliability fine) but these PSU's just won't cut it at the high-end of the market. With motherboards and graphics cards demanding more and more power and at the same time increasing in value it becomes imperative that anyone building a gaming PC buys a quality powerplant to feed the power hungry components enough juice.
So today we are going to take a look at the latest release from OCZ's ModXStream series of power supplies, in this case, the 780w version. Available in two flavours, 780w & 900w, the ModXStream is clearly targeted at the gamer/case modder. With its sleek black casing, modular design and 120mm 'whisper' quiet blue LED fan it is sure to appeal to the masses.
Here's a brief run down of the specification:
Feature list
- OCZ PowerWhisper technology - low noise, load controlled 120mm fan
- Equipped to fuel the demands of Multi GPU gaming systems
- Active PFC & Universal input provides more efficient power/regulates universal input voltages worldwide
- Over Voltage Protection, Short Circuit Protection, Over Current Protection
- Features OCZ ConnectAll universal connectors including ATX12v 2.2, dual PCI Express and S-ATA cables
- Cables contained in flexible trim mesh to promote a tidy environment
- MTBF: 100,000 hours at 25c
- Four +12v outputs for stability and uniform distribution
- Efficiency 80% @ 115v(typical load) 80% @ 230v (Typical load) 
The current on the rails certainly look very capable but these are peak outputs and should not be viewed as 24/7 outputs. Also, the 12v lines appear to give 80A combined but in actual fact, when all the rails are loaded, this figure is reduced to 60A. Still, this is more than enough to power anything but the highest spec PC and 60A on a 780w PSU is certainly impressive. The decision to use a quad rail setup instead of one large rail is and interesting one but for users with SLI/Crossfire setups this setup ensures that the power delivery is being divided equally among the innards of any gaming rig. Heavy overclockers however, may prefer a single large rail ensuring that there is as much juice as possible to power any given overclock.  

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I've always been a sucker for a nicely presented product and from the outset the OCZ didn't disappoint. A thick, glossy, cardboard box hosts the PSU with a clear, yet concise feature list, advertising the PSU's capabilities and benefits. I should, however, point out that the same packaging is also used with the much cheaper StealthXstream range of PSU's from the same company so while the packaging is good, for the price I would have liked something a little more 'special'.  
Front Back
Opening the box I was alarmed to find that the packaging is sparse to say the least. With little more than a layer of cheap bubble wrap protecting the PSU from damage (as well as the box itself), I would not be surprised to find that some PSU's might be damaged in transit. Styrofoam is pretty much standard packaging now among high-end PSU's and is a much more suitable method of protecting heavy items such as a PSU which also works to prevent the PSU from sliding around in the box. I was also mildly disappointed that there was no method of protecting the plastic Molex/SATA/PCIe connectors. Again, for the price of this PSU, I would have liked to have seen some form of pouch used, especially as this PSU is of modualr design. 
Inside Contents
Taking the PSU out of its box I would say that the PSU felt quite light in comparison to other power supplies in the same power range. 'Weight is a sign of reliability' so they say, so while I wouldn't exactly say the PSU is a lightweight, you certainly won't need your spinach to lift it.
Measuring 150 x 140 x 86mm, the PSU should fit in all but the smallest of cases. The matt black finish on the outer EMI (Electro Magnetic Interference) shell is pretty resilient to scratches and should see the buyer through multiple builds without too much cosmetic damage. The most striking aspect of the PSU is of course the blue 120mm fan.
Outer Shell 1 Outer Shell 2
The underside of the casing has no ventilation which will aid the cooling properties of the fan as all the cool air will pass over the internal heatsinks and then be vented through the mesh panel on the units rear. It has to be said that whether the PSU is powered or not it certainly looks the business and despite the poor packaging reported earlier, reached OC3D in pristine condition.
Rear Front
The rear of the PSU is a black mesh affair allowing hot air to escape with the usual on/off power switch situated directly above the kettle lead. There are no diagnostic LED's on the PSU which would have been a nice addition but as the fan lights up it's not so much a problem.  
The sample we had did not have any labels identifying which cable went where and apart from the obvious, there was a little head scratching going on as to where the PCIe cable went being that there was 2 x 8 pin cables (PCIe + CPU) and only one 8 pin port. The instruction manual was of no help whatsoever with regards to connecting the PSU up so it was a case of praying I had them in the right slot (ahem!). This is not exactly what I would have expected on a £100 PSU from OCZ!
Cables & Connectivity
The PSU itself is not 100% modular, with the 20/24pin ATX, 6 pin PCIe and 4+4 CPU cable permanently attached - meaning that if you don't have any use for molex connections this will add to case clutter. However, most gamers/case modders will have some form of cold cathode, LED strip, extra fans that require powering so it is not so much a problem.

All the cables are professionally sleeved and securely heat-shrinked in black, making for a very good looking cable setup.
20+4pin CPU
The 20+4 ATX connector is of a very basic design and doesn't really work as it should. Rather than the 4 pins 'snapping' onto the 20pin connector you have to squeeze both sections together to fit them into the motherboard. I would like to see a simple little sliding mechanism by now as surely it cannot be too difficult to achieve. I cannot really mark the OCZ PSU down for this though as they are only following suit with other manufacturers but it is a missed opportunity nonetheless. The CPU connectors suffer the same fate as well. Along with the above a 6-pin PCIe and a molex cable complete the cabling that is permanently attached to the PSU.
The modular cables come neatly bundled with a piece of Velco preventing them from getting tangled during transit. The cable ends have solid black connectors with the usual snap/lock latches that should last the test of time and are also clearly labelled. The latching mechanism that, while simple, does the job perfectly, preventing any accidental removal of a cable from the PSU. Here is a list of the cables included :
- 1 x 4+4-pin CPU (2 Total)
- 1 x 6-pin PCI-E (2 Total)
- 2 x S-ATA (supporting 6 drives)
- 3 x Peripheral (supporting 6 devices) 
- 3 x Floppy
PCIe Molex
That pretty much covers the external aspects of the case and cabling so let's whip out the trusty screwdriver and take a peek at the ModXstream's guts....

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Internal Components
It should go without saying that you should never remove the cover of any PSU as there is a risk of serious injury or even death but I'll say it anyway. Perhaps less importantly, removing the outer casing will also invalidate the warranty on most, if not all PSU's. So, for your convenience and at the risk of our own health, we will take a quick look at the internal components used in the OCZ ModXstream.
Internal 1
The outer casing also acts as an EMI shield and while being fairly thin it is sturdy enough to protect the innards from shock and tampering. With the four small screws removed (along with the warranty sticker) we get to see the guts of this PSU.
The 120mm cooling fan is a Protechnic MGA fan which is hard-wired to the PSU rather than using the usual 3 pin connectors most often found. The fan is true to its name, being whisper quiet at all but the highest loads and shouldn't interfere with the acoustics of any near silent PC. When powered the fan glows blue from the integrated blue LED's of which there are four.
Busta cap in your ass?
Surrounding the main coil we see 2 small aluminium heatsinks and a single large NEG CapXon capacitor. I would have preferred to see smaller capacitors used rather than a single large one as quite often, large capacitors are more 'noisy' then their smaller counterparts creating ripple among the lines.
Here we see the main transformer for the 12v rails along with the smaller transformer situated behind transforming power to the 5.5 and 3.3v rails.
I was a little disappointed with the overall quality of components used as well as the internal workmanship applied. The soldering and cable tidying was haphazard and in general the PSU looked very amateur. The heatsinks cooling the mosfets also didn't appear to be substantial enough which hopefully is testament to the high efficiency of the PSU and not penny pinching by OCZ. As OCZ now have control of PCP&C who are renowned for making quality PSU's, I would have hoped this partnership would have enabled the designers to create something more than what we have here but looks, as they say, are not everything. Lets see how this power supply performs...

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Load Testing

To provide our readers with the most accurate results, Overclock3D uses a custom-built PSU load tester on all reviews. This not only gives much more reliable results than the testing methods employed by other sites, but also allows for all current and future review results to be compared side-by-side. The following table shows the load (in watts) that was applied to the OCZ ModXstream during testing.
With 0 load the 3.3v line is over-volted slightly but once the load is applied and increased the voltage levels out and is pretty stable throughout the testing period, only dropping below standard as we neared the PSU's limit.
Once more we see that the 5.0v line is slightly over-volted and doesn't drop below standard throughout the PSU load testing. Significantly the rail was very stable ensuring a smooth power delivery to your components.
At the 'money' end of the testing we come to the 12v lines which is a judge of how good a PSU really is. Powering your motherboard, CPU and GPU's, a solid 12v line is essential to maintaining stability over long periods of time. In the OCZ ModXstream's case, we see that it has four rails all of moderate stability with a little over 0.2v movement across the rails when maximum load was applied. It appears that our concerns over the internal layout were unfounded as all the rails have performed well and would easily power a high spec PC without so much of a hiccup.
Efficiency Results
Efficiency tests are performed by measuring the wattage consumed by the power supply at the mains (Mains Draw) against the power consumed by the OC3D power supply stress tester (PSU Load). These results may not be 100% accurate, but have proven to be extremely close to results obtained from professional equipment.
In testing we found the OCZ ModXstream managed to exceed its 80% efficiency rating by over 3% and reaching a phenomenal 86.66% rating at full load which is very impressive indeed, especially when considering this is above the actual power rating of the PSU @ 799w.
Temperature, Fan Speed & Noise
As with all components in the modern computer system, the performance of a PSU can be directly affected by heat. Excess heat inside the PSU can easily have a negative effect of the maximum power output of the unit and lead to voltage instability. For this reason, Overclock3D includes temperature recordings taken from the PSU's exhaust using a thermal probe to highlight any potential issues that the PSU might have obtaining its rated output.
Heat is the number one cause for component failure in a personal computer so it is very important that the powerplant is sufficiently cooled. With the OCZ we found that the heat expelled from the unit was very hot indeed, even with the fan running at full tilt, the heat was a scorching 72c. Obviously those little heatsinks were working overtime in cooling the mosfets down but at this heat I do have a few concerns about the lifespan of the PSU. OCZ however have faith in the longevity as they provide an industry leading 3 year 'PowerSwap' warranty. As expected as the fan RPM rose so did the noise but the fan was still relatively quiet in comparison to other fans found in your average PC case so would not be too intrusive should you fully utilise the ModXstreams supply. 

OCZ 780W ModXstream PSU Page: 5
With modern PC's becoming more power hungry and PC builders becoming more demanding, the PSU arena is rapidly becoming more and more noticeable. The humble PSU, as it should always have been, is now in the forefront of the enthusiasts mind when considering a new PC build. No longer are people satisfied with dull steel cubes with a multicoloured rats nest emitting itself. OCZ, are the answer to many peoples prayers when it comes to stylish yet powerful PSU's and the 780w ModXstream is no different from previous incarnations. With 780w on tap, and a stable, quad rail setup rounded off with a stylish design it should come as no surprise that this PSU comes recommended by many sites. There are however a few little niggles that I would like to point out that others seem to have missed.
A 780w power supply should be enough to power all but the most obscenely hungry PC's, or so you would have thought. The one major fault I found with the OCZ 780w ModXstream is that there are only two 6 pin PCIe cables. While this might appear to be plenty for a single card setup, if your single card happens to require an 8pin PCIe cable then you are out of luck. Much so for anyone wishing to run an SLI/Crossfire rig with the latest generation of cards requiring 2 x 2(4) 6pin PCIe cables, never mind additional 8pin PCIe's. So the ModXstream PSU is severely limiting its target audience to someone who only intends on running a single mid-range card. The PSU is currently available for a bargain price of £77.49 at ARIA but I would be quick to snap this up as the average price on the net appears to be around the £95 mark which, it has to be said, that there are more powerful PSU's available with a greater amount of connectivity at that price point. However, with the £20 saving at Aria this PSU should be given serious consideration.  
The OCZ PSU is a very good, quiet and capable PSU in its own right. With a price revision matching that of Aria , I'm sure it will be very popular as it is possibly one of the best looking PSU's around at this moment in time, especially if you have a fondness for blue LED's! You may however wish to look elsewhere should you want a dual GPU setup which is perhaps the only fault I can level at the OCZ 780w ModXstream.
The Good
The Mediocre
The Weak
Overclock3D Recommended Award
Thanks to OCZ for making this review possible. Discuss in our forum.