Enermax has been towards the top of the power supply manufacturer heap for quite a while, they were one of the first brands to push into the high power (for the time) and high efficiency (for the time) arena that we all take for granted now. Today’s unit is much higher wattage and much higher efficiency than those past units of course, but you can smell the history. Or possibly the solder fumes. In any case, let’s see how the MAXREVO performs!
Below you will find the Features list brutally borrowed from Enermax’s website. My comments on things are in italics.
|I still have no idea what they’re talking about.|
|This looks promising though.|
I guess what the FMQ thing really translates to is that the transformer is far smaller than it otherwise would be. That sounds good to me.
We don’t get much of a specs list, but it does list the maximum rail loadings. We get 4 amps of 5VSB here, that’s nice and juicy. Enermax does thoughtfully provide a nicely detailed list of cables though:
That last cable is an interesting one, it has both the ATX24P connector and the CPU power connector on one end, and two plugs on the other end. The two plugs on the PSU end allow for the use of extra pins/wires for the regulators to use for voltage sensing. Combining the motherboard and CPU power plugs makes sense from the standpoint that you’re going to be using both. We’ll look at the cables that actually showed up in the box in a bit.
Photos Part One: The Box
What we’re actually looking at is a sleeve that goes over the flat black box. At some point between factory and my doorstep the sleeve got a bit mangled as you can see. I regard the shipping process as part of the review, but I really don’t care what condition the box is in as long as the PSU survives.
Inside the box are three more boxes with open tops, I’ll spare you the excessive box-in-box-in-sleeve shots and go straight to the minor boxes and accessories.
I found a power supply! A very compact power supply for the 1500 W rating, at that.
Photos Part Two: The PSU Itself
I am fond of crackle-black finishes. Add some gold details and stamped in chevrons and we’re set! At least, Enermax hopes so.
The modular cable connectors are all nicely color coded, though they don’t tell you which rail goes where. Thankfully there is a sheet in the box that does list them for us:
Given that Enermax rates the rails for 30 amps each, you don’t want to put two top end GPUs (which eat between 16.6 amps and 30 amps depending on generation and single/multiple cores) on one rail. Enermax doesn’t say what the OCP trip points are, but overloading rails is never a good idea. At one GPU per rail we still get four GPUs worth, so that’s fine.
In the interest of adding more pictures, here are a couple more pictures:
Lastly, some detail on the CordGuard mentioned in the features list. There are a pair of loops sticking out below the AC power cord and a wire clip arrangement included in the box. Getting it together is a bit of a puzzle, but here’s what you end up with:
Not likely to go anywhere once you’ve gotten it clipped in there. That’s good, as this unit can potentially draw a lot of current from the wall and you really don’t want a bad connection there. I’d prefer a C19 plug here.
While we’re on the topic of cables…
Photos Part Three: Cables
First up, the primary cables that everybody will use:
On the left are the main ATX24P and CPU power connectors. Neither of them are split, so good luck using this unit with old parts. On the right in the left photo is a bonus CPU power cable, it has one 8P and one 4P connector, giving us enough CPU power cables for pretty much anything. In the right picture is the PSU end of the ATX24+ cable, showing the voltage sense wires for 12 V, 5 V, 3.3 V and GND.
I like the cable selection. Enermax includes a nice, juicy power cord too.
That does it for photos, now it’s time for testing!
Testing Part One: Regulation Testing
A decent load test of a PSU requires a decent load. Contrary to what some may believe, that means you need a known load that can fully stress the PSU. Computer hardware does not cut it. Worse, if the PSU fails during testing it might take out the computer hardware anyway. Commercial load testers cost a lot of money. I do not have a lot of money, so I built my own with juicy power resistors and a Toyota cylinder head. It works great. I’ll be using it to load this thing down fairly severely and will check voltages and ripple (more on that later) at various points. The down side to my tester is that the loads it can put on PSUs are fairly coarse, they go in increments of 48 W for 12 V, 50 W for 5 V and 22 W for 3.3V. Those wattages assume the PSU is putting out exactly the official rail voltage, a PSU putting out 12.24 V rather than 12 V will be at 49.9 W per step rather than 48 W. I file that under the “tough beans” category as I figure if a percent or two of load makes that much of a difference, the PSU manufacturer should have hit the voltage regulation more squarely. It does make calculating efficiency difficult at best. However, given that the input power is read via a Kill-a-Watt, the efficiency numbers are dubious to begin with. Kill-a-Watts are not known for extreme accuracy on things with automatic power factor correction. For this reason, I am not listing the efficiency.
The ATX spec says that voltage regulation must be within 5% of the rail’s official designation, regardless of load. It doesn’t actually mention that the PSU shouldn’t explode, though I expect they figured it was implied. Exploding is a failure in my book regardless.
It is also worth knowing that I will be testing this PSU at both outdoor ambient temperatures (typically between 10 °C and 20 °C here this time of year) as well as in the Enclosure of Unreasonable Warmth. TEUW is a precision engineered enclosure that I use to route the exhaust air from the PSU right back into the intake fan, it is adjustable to hold the intake air temperature at (almost) any level I want it. This way I can test the PSU’s response to hot conditions as well as cold conditions. For the hot testing I will be running the intake temp as close to the unit’s maximum rated temperature as possible. TEUW, in case you’re curious, is a cardboard box.
|Wattages (total)||12 V Rail||5 V Rail||3.3 V Rail||Kill-A-Watts||Temps|
|HOT RESULTS BELOW|
The good news is, the unit really can do 1500 W! It can do it with a sustained 41 °C intake air temperature, too. It managed to pop the circuit breaker on both the power strips I tried, so keep that in mind when you’re selecting a surge protector for this monster! The surge protector needs to be rated for at least 1700 W continuous.
Regulation on the 12 V rail was 3.6%, not great. I’ll call it OK, as it’s well within the spec and certainly functional. Regulation on the 5 V rail was 0.19%, fantastic! The 3.3 V rail had 0.89% regulation, also extremely good. All told that averages out to 1.15% regulation. Anything under 1% is fantastic, 1.15% is very very good. I’m still disappointed in the 12 V regulation though. It really looks like the vsense wire wasn’t doing anything useful for the unit, I checked in the dissection process and it’s wired correctly all the way to the controller though. Oh well.
The fan makes some airflow noise at idle as well as a slight buzz. I doubt you’d notice it in a case, especially not a case that can house (and is housing) 1500 W worth of computer bits. At full load there is significant airflow noise, though nothing even close to say the NEX1500. I’d say it’s fairly quiet for a 1500 W unit. There is also an electrical hum, likely from the MOSFETs and transformer inside having to switch an awful lot of power. Nothing terrible though by any means.
All told the regulation testing report is “good”.
Testing Part Two: Ripple Testing
Ripple is fluctuation of the PSU’s output voltage caused by a variety of factors. It is pretty much impossible to have zero ripple in a SMPS computer power supply because of how a SMPS works, so the question is how much ripple is there? In the regulation testing phase we found out how the PSU does at keeping the average voltage at a set level, now we’re going to see what that voltage is doing on really short time frames. The ATX spec says that the 12 V rail cannot have more than 120 mV peak to peak ripple, the 5 V and 3.3 V rails need to stay under 50 mV.
If that isn’t complicated enough for you, there are three forms of ripple to keep track of as well. Long-term ripple from the PSU’s controller adjusting the output voltage and over/undershooting, correcting, overshooting, etc. Medium-term ripple from the voltage controller charging and discharging the inductor(s) and capacitor(s) that make up the VRM, and very short-term ripple caused by the switching itself. The first and second forms are the most important, if they are out of spec it can cause instability at best or damage in extreme situations. The very short-term (I call it transient ripple) flavor is less crucial, excessive amounts can still cause issues though it takes more of it to do so. The ATX spec does not differentiate, as far as the spec goes 121 mV of transient ripple is just as much of a failure as 121 mV of medium or long term ripple.
I test ripple in a few difference ways, first I test it during the cold load testing. It is tested at zero load and maximum load first. During the hot load testing I test the ripple at maximum load again. I have recently started testing ripple at fairly random loads with the unit still hot, it’s a bit unorthodox (a bit? maybe a lot) but has found issues in the past that did not show up with other test methods.
First up, zero load and cold ambients. Scope is set to 5 µs / div and 10 mV / div for 12 V and 3.3 V. 5 V had an interesting hump in it that was only visible with a slower speed, so for 5 V the scope is set to 5 ms / 10 mV.
Cold ripple is good, just under the 50% line (on 5 V and 3.3 V) for a “good” rating. The 3.3 V rail and 5 V rail were essentially identical at both settings, hence showing slow speed on 5 V and fast on 3.3 V. That way you get to see both flavors of ripple without having a bunch of extra pics. The 12 V ripple is very good, though I have to say that seeing the the switching transients at zero load makes me a bit nervous.
Normally we’d have full load cold ambient shots here. Unfortunately the photos I took turned out to be junk due to the particular path my scope lead’s cable was taking past the PSU. This PSU puts out a lot of EMI through the fan grill, If the scope probe cable is anywhere with the fan facing it, the switching transient readings went through the roof. This is a PSU to mount in your case fan down! The PSU’s case acts as a Faraday cage and keeps the EMI contained, but there’s no case over the fan, so some escapes that way. I doubt that it would cause any issues even if aimed right at your GPU(s), but if you’re planning on OCing heavily and running on the edge of stability, they aren’t likely to appreciate electromagnetic hell much.
The 40 °C results had TEUW to keep the cable away from the PSU, so they survived. For all three rails the scope is set to 5 µs / div and 20 mV / div.
Here at full load and high temperatures, the ripple picture isn’t quite as rosy. The 12 V rail is only a hair over the 50% mark, that’s pretty good in general and very good for 1500 W. The 5 V rail is over the limit, you’ll probably have to click the picture to see it but the switching transients are ~56 mV. That’s over the 50 mV limit even if we take into account the +/- 2 mV of scope accuracy / environmental ripple. Not a lot over, not enough to actually cause problems, but it’s over. 3.3 V stays within spec, which is good.
The 5 V rail is likely picking up EMI inside the PSU case more than anything else, not much to be done about that other than more output filtering on that rail.
All told I’ll give the overall ripple picture an OK.
Disclaimer: Power supplies can have dangerous voltages inside them even after being unplugged, DO NOT OPEN POWER SUPPLIES. It’s just not a good idea. Opening a power supply and poking around inside could very well kill you. Don’t try this at home. Don’t try this at work. Just don’t do it.
With the cover removed, we find the fan and a whole bunch of stuff tacked to a PCB:
There’s an amazing amount of empty space for a 1500 W PSU, pretty wild really. An interesting thing to note is that the exhaust grill end of the PSU has some armor to keep the grill away from high voltage should it get kicked in. I like the attention to detail. The two screws prevent the grill from coming in, and even if it does the transient filter inductor and APFC inductor both have insulation/armor on them as well.
Let’s step through it, starting at the receptacle and the transient filter.
The receptacle contains a transient filter inside a metal can, that part has an X cap, two Y caps, and two inductors. On the PCB we have four more Y caps, another X cap, three inductors, a TVS diode and a chunky fuse. We have a very nice transient filter here.
Moving along the next suspect is the APFC section.
The rectifier is a LL25XB60 (25 A, 600 V) monster, the MOSFETs are a pair of 35N60C3 (22 [email protected]°C, 34.6 [email protected]°C, 600 V) jobbies, the diode is a very well hidden CREE C3D10060 (10 A, 600 V) unit. We also get three Panasonic capacitors, two rated at 330 µF and one at 390 µF, all are rated at 400 V. There is also a thermistor for inrush protection as well as a relay to short it out once the unit has started. Controlling the whole operation is a ICE2PCS02 brainbox.
The primary brains are a TI UCC28950, it also runs the 12 V rectification MOSFETs. For switches we have four K18A60V MOSFETs that I can find no data on. 18 amps and 600 volts seems likely though.
Before we step through the secondary side, a couple overview pictures:
The rectification setup is interesting, the main PCB is set up so that it can use normal MOSFETs in the same package as the APFC bits, or it can have a daughterboard soldered onto it that allows the use of rather a lot of TO220 type MOSFETs. In this unit, the second option was chosen.
You can see the daughterboard there, it’s brilliant really. The 12 V rail gets eight APM2556N (160 [email protected]°C, 90 [email protected]°C, 25 V) MOSFETs. 5 V and 3.3 V each have a APW7073A driving four APM2556N (160 [email protected]°C, 90 [email protected]°C, 25 V) MOSFETs. Nicely overbuilt in both cases!
The 12 V caps consist of a bank of Rubycons spanning the entire width of the unit! One of them had some gunk on it that Enermax says it glue from the tape they come attached to. I pulled the cap off and tested the goop, it’s non-conductive. The capacitor itself has no visible damage even under 160x magnification, so while it looks like electrolyte to me, it almost certainly is not. In any event, Enermax promised to look into things to prevent future occurrences. The modular power board is attached to the main PCB by a series of standoffs and (very, very tight) screws, six shunt resistors are present as well, indicating that we really do have six 12 V rails. The protections IC is a PS238 chip, which supports six 12 V rails as well as 5 V and 3.3 V, for OVP/UVP/OCP. It also has an input for OTP.
The modular power board and the DC-DC board are mounted back to back with a sheet of plastic between them, so I can’t see much of the soldering on either one. Here’s the connector end of the modular board though, as well as a soldering overview:
Soldering quality ranges from good to very good, it’s better than average but not as clean as some. Certainly no issues though. You can also see a series of shunts on the primary side for OPP (on the ground path, interestingly).
All together it’s a well built unit with no meaningful issues. The odd capacitor is the only dent in the otherwise perfect bill of health, and given that it doesn’t appear to be electrolyte and the unit tested just fine, I’m not going to hold it against the unit.
Final Thoughts and Conclusion
The big question in my mind when I received this unit was “How will it compare to the NEX1500?” The answer to that one is “very well”. The cables are easier to use, it comes with a logical and accurate map of the rails, no chrome bar, and a far lower price. I like it!
We’ll take it from the top, the amount of padding the PSU gets in transport is disappointing to me. It’s better than nothing, but I like full foam surrounds better.
The unit itself looks pretty nice, the gold fan surround and text may not be for everybody, but it’s a nice looking unit. It’s also very compact, which is impressive.
I like the power cord clip, and that the power cord is a C19 type rather than a C14. That makes me happy.
The cable options are quite good, if the lack of split CPU and Motherboard power cables is an issue for your board, it’s time to upgrade. The sleeving on the cables is Enermax’s usual distinctive weave and is pretty snazzy looking. If you’re going for a stealth black look, they may not be for you though.
The regulation on the 12 V rail was surprisingly loose given the 12 V sense wire, but still well within spec. The 5 V and 3.3 V rails were excellent, and dragged the average back down into the “Very Good” range.
Not many people actually need a 1500 W PSU, especially as modern GPUs are trending towards lower TDP. That said, if you have four 7970s and a 3930k/3960x and want to overclock, it’s time to think about a 1500 W PSU!
The fan is on the quieter end for a 1500 W unit, but is definitely not silent. We get a hum at full load too, though not a loud hum.
12 V ripple control is good to very good. 5 V is 6 mV over spec, which is unfortunate. 3.3 V is just under spec, which isn’t fantastic either. You probably won’t be pulling 50 W on the 5 V rail and even if you are, 6 mV isn’t likely to cause any issues. But the spec is the spec.
The component choices are excellent, plenty of headroom. The transient filter is excellent as well, no issues design wise at all.
The build quality is very good as well, ignoring the one oddball cap, which I am ignoring.
The current retail price is $370, putting this unit squarely in the middle of 1500 W units. You can get an 80+ Silver 1500 W PSU for anywhere from $300 through $400. Gold units range from $330 for the LEPA version of this same unit (though rated at 1600 W), up to $450 for the NEX1500. The only real competition price wise is from the LEPA unit, which has a 100 W higher rating but lacks the receptacle transient filter among other things. I call this a good price, especially given the quality of the unit.
I’ll summarize this a bit, as it’s gotten a bit unwieldy:
There are pros!
- Really does 1500 W, easily.
- Good price.
- Looks great.
- Plenty of cable / connector options.
- No mystery which PCIe cable goes to which rail.
- Remarkably quiet for a 1500 W PSU, hum and all.
- Quite compact for a 1500 W PSU.
There are cons, too:
- 5 V rail 6 mV over spec at full unit load.
- 12 V regulation looser than expected (but within spec easily).
- Packaging could have more foam.
At the end of the page and the bottom of the day, there isn’t much of anything standing between the Enermax MaxRevo 1500 W and the Overclockers.com approved stamp. It’s a very solid unit at a good price. The only possible dent comes from the niche market that actually needs a 1500 W PSU, but those people are out there and Approved this unit is!
— Ed Smith / Bobnova