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XG Duro 900 Power Supply

Date: April 25, 2006
Author(s): Matthew Harris

If the motherboard is the brain of any PC then the power supply is the heart. Today we’re taking a look at a power supply that has all the heart you should need for any modern enthusiast system and the cost won’t put your wallet on life support.


The Duro 900 comes in a box that can best be described as stealth. No loud colors, just a basic black that is low gloss and happily very photogenic. On the box XG takes the time to list the features of the PSU. I’ll list them down so you don’t have to squint to make them out:

All in all that’s pretty straightforward. Normally with smaller companies they try to dress up the list with double talk that sounds impressive but actually makes no sense. There’s none of that here.

On the other sides of the box XG lists tech specs such as minimum and maximum voltages by spec, shutdown voltages and features. They also include a couple of graphs showing the stability of the Duro’s wattage versus the derating of other brands and how the fan speed increases as the wattage load increases.

Inside the Box

Inside the box lives the PSU and the manual and 4 mounting screws. Nothing out of the ordinary. The PSU is your basic black with fully sleeved cables. No modular plugs and no chrome finishes here. There is a gold grill on the rear of the PSU and the power switch has a neon bulb in it to let you know it’s powered up. The switch remains lit whether or not the switch is on though so it’s only useful in indicating that the source to the PSU is powered up, you can’t tell that the PSU is on or off at a glance.

Sadly mine didn’t include a 24 to 20 pin converter which means that if you’re using this PSU on an older mobo that doesn’t have a 24 pin ATX connector you’ll have to let the other four pins hang off the end. It will work with some boards but others will have difficulty due to crowding around the ATX plug. Since I’m on the subject I’ll list the rest of the connectors.

Going by the wiring colors it looks like the 12V rails are split up as follows 12V-1 to drives, 12V-2 to CPU, 12V-3 & 4 to motherboard and PCI-e connectors. Not quite following the split plane specs but it does insure that the PCI-e cards have plenty of power to pull from.

I’ll once again let the label do the talking on the specs for the rails but I do have to interject something here. According to the manual the PSU has several different wattage claims. At one point it states 900W continuous. At another it states 170W on the 3.3V and 5V rails and 685W total on the 3.3V, 5V and all the 12V rails with 700W overall. I’d like to see this straightened out as it’s confusing.

And without further ado, the guts of the PSU:

Yes, this is a dual sided PSU. Kind of reminds me of the Ultra X-finity 600W but unlike the Ultra the Duro isn’t pulling rail voltage from the upper board. Instead the Duro is using the upper board for the active PFC circuitry. Sadly I couldn’t fully split the two halves of the PSU completely apart due to the majority of the control cable connectors being glued into their sockets but I was able to unplug the power connector and give you a good view of the boards by holding them apart.

Looking at the bottom PCB we see that the Duro is made by Seventeam and carries their model number of ST-750EAX-8. Looking at Seventeam’s site they list the 750EAD model as a 750W. The 750EAD features all the same rail specs as the Duro and is a single 80mm fan PSU. Even if the Duro is in reality a 750W PSU it’s still a monster and should be more than most people would use.

Looking at the insides you can see just how extensive the PFC circuit is. I also like the fact that toroids are used throughout for the majority of transformer duties. For those that don’t know, toroids cost more to manufacture and are generally considered to be preferable over ferrite core transformers.

I think part of that is the design of a toroid helps to shed heat due to the coil being open to airflow and not tightly wrapped and taped. As we all know heat is the enemy of electron flow. As heat increases in any component the resistance to electron flow increases. This cuts down on voltage and amperage. This could explain how the Duro could live up to it’s ability to deliver stable wattages even under high temperature conditions.

You’ll note I didn’t say rated wattages as that’s still up in the air. I spoke to the rep about this issue and he said it would be amended in the manual and on their site but as of this writing it’s still the same on the site and in the PDF version of the manual.

Testing and Conclusion

I’ll be comparing the Duro to a PC Power & Cooling 850SSI on the following system

To load the system as hard as I could I started a file transfer on the LG to the 400 gig drive, fired up Super Pi mod 1.04 and ran 3D Mark 06. The rails were all tested using a digital multimeter during load runs and with the PC at full idle.

Onward to the numbers. Bear in mind that due to the non-standard rail setup on the Duro the 12V rails are by my best estimate as to which is 12V3 and 12V4.

Overall the voltages are a tad high but easily in spec. the droop under load wasn’t bad but more pronounced than the PC Power & Cooling unit. Is this a bad thing? Not when you consider that the 850SSI costs nearly 3 times what the Duro 900 does. The Duro is very stable though, after the droop the voltages had barely any fluctuation during the load tests. I can live with rails that drop .04V under load compared to .01V when it’s saving me literally hundreds of dollars.

As an added bonus the Duro is drastically quieter than the 850SSI, the SSI has a very noisy tri-bladed fan that really defeats the purpose of building a quiet PC by using water cooling to ditch noisy fans. The fan on the Duro while not silent was hard to distinguish from the cooling fans and radiator fans until the PC was loaded. Upon loading the system to 100% the PSU started getting warmer and the fan speeded up but unlike the other the fan noise went up in air sound not in a high pitched whine. The soft susurrant of moving air is preferable versus the hard whine of fan blades in my book.

When it’s all said and done I’m giving the Duro 9/10 for its ability to do the job and do it well. The confusing manual and lack of 24 to 20 pin adaptor prevents it from getting a perfect score. If you’re into bling you might knock it for that but to me bling is secondary to ability and that’s where the Duro shines, it has the ability to run damn near anything you could throw at it. I’d like to thank the good folks at MGE/XG for sending the Duro 900 to me to rip apart for you.

April 25 Addendum: After contacting the rep for MGE about the issues I encontered with the Duro I was informed that MGE will send current Duro owners a 20 to 24 pin adaptor if they will contact the RMA department and the manual will be updated in the next revision to be a little less confusing as to the wattages.

April 27 Addendum: Today (04/27/2006) I spoke with MGE’s rep about the issues surrounding the true wattage of the Duro. Yesterday I had received an email from the project manager telling me that the Duro does 820W cold, 900W peak and 750W at 50°C. After speaking to MGE’s rep about this issue since he hadn’t seen this as I found out after he was out of the office he assures me that the Duro will be re branded as a 750W PSU and the current stock will have the packaging changed to reflect this fact and new stock will have new packaging that shows 750W rather than 900. Was this a conscious effort to defraud hardware buyers? I honestly don’t know but I do know that it’s not acceptable to label a product with specifications that aren’t true.

After consideration of these facts I’m changing my final score to a 7/10 and docking a full 2 points for the over-rated wattage on the unit I got. Due to MGE promising to make it right in regards to the labeling I’m not dropping the score further. As a $150 750W @ 50°C it is still a good deal but the wattage rating might be a stain on the reputation of the Duro that haunts it for some time to come.

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