OCZ GameXStream 850w ATX PSU Page: 1

Just over 2 months ago I was given the opportunity to review OCZ's high-end 700w GameXStream unit. Proving that performance, silence and efficiency could all coexist in a small ATX sized package led to the unit nabbing our "Editors Choice" award. Since then OCZ have been hard at work tweaking the existing design and uprating components to push a further 150w out of the GameXStream's excellent design.

In essence, the 850w GameXStream is visually the same in every way as the 700w unit (externally at least), and for this reason I'd suggest that anybody who has already read our 700w GameXStream review should turn to pages 5, 6 & 7 to avoid a severe case of Déjà Vu. Over these few pages I'll be looking to answer the question:- Is there really such thing as a normal ATX sized, silent, efficient power supply capable of delivering a stable 850w?


The graphical design of the packaging is certainly aimed to turn heads. Using a dark blue/black background complete with power/lighting effects bolting into an image of the GameXStream unit, this is probably one of the first units people will pick up when browsing for a new power supply in a computer store.

OCZ GameXStream 850w Box Top OCZ GameXStream 850w Box Front

The information on the front and top of the packaging tells pretty much the same story: 850w, 36month warranty, Dual GPU ready, Active PFC and many other features to boot.

OCZ GameXStream 850w Box Back OCZ GameXStream 850w Box Side

The trend continues around the side and on the back of the packaging, once again showing a picture of the unit alongside some of its vital statistics.

It's also good to see that OCZ have placed their support e-mail address on the back of the packaging should you have any problems with the unit. During the review of the OCZ GameXStream 700w, we actually put this address to the test. Within 42 minutes of sending an e-mail complaining about a faulty unit, we received a reply from a real person giving us information on what else is should try before completing an RMA application. Impressive.

OCZ GameXStream 850w Box Open OCZ GameXStream 850w Package

The GameXStream is packaged in a clear bubble-wrap bag to protect it from knocks and scratches. Hopefully this should be enough to protect the unit from moderately rough handling by couriers during its journey to you. Included in the box are the following items:

• 4x Black ATX screws.
• 1x Power cord.
• 1x GameXStream colour manual
• 1x Velcro cable tie
• 1x GameXStream PSU

OCZ GameXStream 850w ATX PSU Page: 2

The following specifications have been shamelessly copied from OCZ's website:

"The SLI-Ready GameXStream 600/700/850w Watt power supplies are designed specifically for the demanding computing environments of PC Enthusiasts, Power Users, and Gamers. As more and more gamers take advantage of the gaming benefits offered by multi-GPU technology the need for improved power supply solutions increases greatly.

The GameXStream features high-quality components to ensure your PC’s vital hardware is supplied with clean, stable and reliable power without compromising effectiveness. ...."

• 600W, 700W & 850w Configurations
• NVIDIA® SLI™-Ready
• OCZ PowerWhisper™ Technology
• Internal 120mm fan
• 3 year warranty backed by OCZ’s exclusive PowerSwap™ replacement program.
• 150 x 140 x 86mm
• ATX12V v2.2 and EPS12V
• OCZ ConnectAll™ universal connectors:
°° 1 x 20+4Pin ATX
°° 1 x 4-pin/8-pin CPU (supports double CPUs/supplies stable voltage)
°° 2 x PCI-E 6 x 4-pin peripheral
°° 2 x 4-pin floppy
°° 6 x S-ATA
• High efficiency 80% @ 115V (Typical load) 83% @ 230V (Typical load)
• Overvoltage/Overcurrent/Short-Circuit protection
• Active PFC • MTBF:100,000 hours
• 100~240Vac 10-5A 50/60Hz
• Rail output (Maximum ratings are shown):
°° +3.3V(36A)
°° +5V(30A)
°° +12V1(18A)
°° +12V2(18A)
°° +12V3(18A)
°° +12V4(18A)

What I found most strange about the GameXStream's specifications was both OCZ's website and the PSU packaging listed each of the units +12v rails at 18 amps. However, as you will see on the next page the specification sticker on the actual unit rates these rails at 20 amps each.

OCZ GameXStream 850w ATX PSU Page: 3

As a bit of a generalisation, products aimed at the gaming community tend to be filled with flashing lights and covered in UV reactive components. I was expecting a similar approach from OCZ considering that (judging by the name) this unit is aimed squarely at gamers.

However, on unpacking the unit I was presented with a power supply very much on the subtle side...

OCZ GameXStream 850w Top OCZ GameXStream 850w Back

The OCZ GameXStream is finished in a matt black paint, a rather disappointing step away from the gunmetal finish found on the recently reviewed EvoStream unit. On the upside though, I guess owners of the GameXStream won't have to be so careful not to cover the unit in fingerprints, a problem which plagued owners of OCZ's previous ModStream and PowerStream units.

OCZ have chosen to cool the unit with a single 120mm, blue LED fan which is covered by a black painted grill. This is becoming a popular method of cooling, as it is much quieter and often more effective than utilising several 80mm fans.

The back of the unit sports a honeycomb mesh, allowing the hot air moved by the 120mm fan to exit out of your case with minimum restrictions. The GameXStream, like many other modern PSU's is able to auto-detect the input voltage, and therefore does not require a voltage selection switch often seen on older power supplies.

OCZ GameXStream 850w Side OCZ GameXStream 850w Front

The front and sides of the unit are rather uninteresting with small grills placed near areas of the unit most likely to produce heat. The OCZ sticker shows the units peak outputs along with the usual warnings about not opening the PSU cover.

OCZ GameXStream 850w ATX PSU Page: 4

All cables on the GameXStream are finished in black sleeving, with the molex connectors adopting the 'easy grip' design. This not only improves their appearance but should also make removal of the connectors from devices easier.

OCZ GameXStream 850w Cables OCZ GameXStream 850w Cables

OCZ GameXStream 850w Cables OCZ GameXStream 850w Cables

It's also good to see that OCZ have decided to sleeve all cables right to the tip. Many manufacturers only sleeve some of the cables, or sleeve up to the first connector on every cable. The sleeving job is professional with cable ties holding the sleeving in place, and heat shrink keeping everything neat and tidy.

OCZ GameXStream 850w ATX OCZ GameXStream 850w P412v

The ATX connector on the GameXStream is native 24-pin. However, as you can see above, a small block of 4 connectors can be broken off to switch the connector to 20-pin, and thus make it compatible with older motherboards. This is also true for the 8-Pin EPS12v connector which can be split in half, providing the user with a 4-Pin P4-12v connector.


SATA Molex Floppy

With 6 SATA connectors, 6 Molex connectors and 2 Floppy connectors the GameXStream 850w should have enough plugs to suit almost every configuration of PC.

OCZ GameXStream 850w ATX PSU Page: 5
Looking Inside

As with all power supplies that pass through Overclock3D, I'll be taking a look inside the GameXStream. By doing this I should be able to get a good idea of the overall build quality of the unit and how it is likely to perform in our tests.

OCZ GameXStream 850w Inside OCZ GameXStream 850w Inside

Very little appears to have changed inside the GameXStream since we last visited it in its 700w form. One of the most noticeable differences has to be the upgraded aluminium heatsinks, which no doubt assist in removing the extra heat produced by the 150w bump in output.

For those of us who are used to power supplies with beefy components inside, the layout of the GameXStream may come as a bit of a shock. However, don't be afraid - the GameXStream unit works slightly differently to your average power supply and manages to produce excellent results from its conservative interior.

OCZ GameXStream 850w Rating OCZ GameXStream 850w Pot

During a closer inspection of the GameXStream, I came across what appeared to be an adjustable potentiometer (pot for short). Pot's can be used to adjust the voltage output by the rails on the power supply, and can come in handy when voltages droop outside of ATX specifications.

It also looks like OCZ might be planning on producing a 900w version of the unit, as the bottom left of the PCB has an array of tick boxes ranging from 400w to 900w.

OCZ GameXStream 850w Fan

Cooling the GameXStream is the very same fan used in the 750w GameXStream. Manufactured by Protechnic Electrics, the MGA12012HB spins at 2500rpm with a noise output of 38.3dB when running at 12v. The fan also includes a blue LED to brighten things up a bit!

OCZ GameXStream 850w ATX PSU Page: 6
Load Testing

In order for the results from all current and future PSU reviews to remain fair and comparable, Overclock3D uses a custom built Power Supply load stress tester. The tester will be placing the following loads on each of the GameXStream's rails:

+3.3v - 20a Load
+5.0v - 20a Load
+12v1 - 15a Load
+12v2 - 15a Load
+12v3 - 15a Load
+12v4 - 15a Load

The results are collected from a Mastech MAS-345 Multimeter which logs its readings via RS232 to a PC.

OCZ GameXStream 850w +3.3v OCZ GameXStream 850w +5.0v

Good results from both the +3.3v and +5v rails here. Neither dropped by any significant amount and both remained well within ATX specifications. These results are slightly better than the recently reviewed GameXStream 700w which just goes to show that OCZ have been working on improving the performance of this unit in all areas.

OCZ GameXStream 850w +12v1 OCZ GameXStream 850w +12v2

OCZ GameXStream 850w +12v3 OCZ GameXStream 850w +12v4

Once again the GameXStream 850w produces excellent results, keeping fluctuation on all +12v rails to a minute 0.01v and even in one case 0.00v. Very few power supplies we've tested at Overclock3D have managed results this good thus putting the GameXStream among some of the best units on the market.

Efficiency Testing

Efficiency tests are performed by measuring the wattage consumed by the power supply at the mains against the power (in watts) consumed by the OC3D power supply stress tester. These results may not be 100% accurate, but have proven to be extremely close to results obtained from professional equipment.

OCZ GameXStream 850w Efficiency

The GameXStream was placed under a load of 886 watts. This counts for a total of 104% of the power supplies rated output. At this load, the power supply required 1033 watts from the mains. Therefore the efficiency of this power supply can be found by a simple equation: (886 / 1033) * 100, which works out to be an efficiency rating of 85.7%.

Noise Testing

Possibly the hardest part of any PSU review is summarising the level of noise given out by the unit. The threshold for what is considered 'noisy' varies from person to person and therefore what I may consider a quiet unit, another person may consider extremely loud. A common way to resolve this issue is to use a dBA meter to measure the units noise level, however this doesn't take into account the pitch (type) of noise emitted and whether it is likely to irritate end users.

For this reason OC3D records all power supplies at idle and load in wav format for you to make your own informed decisions. All recordings are taken at 30cm away from the PSU and outside of a PC case. You will need to remember that noise levels will be reduced by varying amounts once the PSU has been installed inside your PC enclosure.

Idle Recording - Download
Load Recording - Download

I was pleasantly surprised by the low noise levels emitted by the GameXStream both at idle and under load. Most high wattage power supplies seem to have trouble maintaining low noise levels when under full load, however the GameXStream managed this effortlessly.

OCZ GameXStream 850w ATX PSU Page: 7

When talking about power supplies, the general rule of thumb is more power = more noise. This is because in order to combat the extra heat produced by higher wattage power supplies manufacturers need to install more powerful (and noisy) cooling solutions.

However, this rule has been totally disproved by the OCZ GameXStream, which managed to produce a full and stable 850w of power without the noise and heat associated with other high wattage units we've tested in the past. Add to this the fact that the OCZ GameXStream is no bigger than your average ATX power supply along with its excellent efficiency level of over 85% (as tested by our equipment) and it's hard to even consider using another power supply for your high-end future gaming PC.

In recognition of these excellent qualities I need to congratulate OCZ for being the first company in the history of Overclock3D to receive our "Best In Class" award. This award signifies that the OCZ GameXStream 850w PSU is considered by Overclock3D to be the best all-round power supply in the 600w - 900w classification.

The OCZ GameXStream 850w is currently available from Specialtech for the very reasonable price of £115.

• Rock stable voltages.
• Ultra-high efficiency.
• Very silent for an 850w PSU.
• Fully sleeved cables.
• 36 month warranty with fast support.
• Internal adjustable potentiometer.
• Standard ATX size (amazing for a unit with this much power).

• Nothing worth talking about. A first for any PSU here at OC3D!

Best In Class

Thanks to OCZ for providing this unit for review.

Discuss this review in our forums.