Riotoro Enigma 850W PSU Review

A Look Inside And Component Analysis

Parts Description

Before proceeding with this page, we strongly encourage you to a look at our PSUs 101 article, which provides valuable information about PSUs and their operation, allowing you to better understand the components we're about to discuss. Our main tools for disassembling PSUs are a Thermaltronics soldering and rework station, and a Hakko FR-300 desoldering gun. Finally, for the identification of tiny parts we use an Andonstar HDMI digital microscope.

General Data
Manufacturer (OEM)Great Wall
Original PlatformGW-ATX850BL
Primary Side
Transient Filter4x Y caps, 2x X caps, 2x CM chokes
Inrush ProtectionNTC Thermistor & Diode
Bridge Rectifier(s)2x  GBU1508 (800V, 15A @ 100°C)
APFC MOSFETs2x Vishay SIHG33N60E (650V, 21A @ 100°C, 0.099Ω)
APFC Boost Diode1x CREE C3D08060A (600V, 8A @ 152°C)
Hold-up Cap(s)2x Rubycon (400V, 390uF each; 780uF combined, 85°C, USG)
Main Switchers2x Fairchild FCH104N60F (650V, 24A @ 100°C, 104mΩ)
APFC ControllerChampion CM6500 & CM03AX Green PFC controller
Switching ControllerChampion CM6901X
TopologyPrimary side: Half-Bridge & LLC Resonant Converter
Secondary side: Synchronous Rectification & DC-DC converters
Secondary Side
+12V MOSFETs4x A-Power BV6N19
5V & 3.3VDC-DC Converters: 4x AP0403GH FETs (30V, 50A @ 100°C, 4.5mΩ)
PWM Controller:1x APW7159C
Filtering CapacitorsElectrolytics: Elite (3-5,000 @ 105°C, EJ), Teapo (3-6,000h @ 105°C, SY), 2x CapXon (105°C), 1x Chemi-Con (105°C, KY)
Polymers: Chemi-Con, 2x FPCAP (VRMs), 2x CapXon* , 2x Elite*
*Modular PCB
Supervisor ICSitronix ST9S429-PQ14 (OVP, UVP, OCP, SCP, PG) & AS358 (Dual Op-Amp)
Fan ModelHong Hua HA1425L12F-Z (140mm, 12V, 0.22A, 1800 RPM)
5VSB Circuit
Rectifier1x PFC PFR30L45CT SBR (45V, 30A)
Standby PWM ControllerPower Integrations TinySwitch-III TNY278PN

This platform is provided by Great Wall and it is exactly the same as the one used for Corsair's CS850M. The quality of the bulk and filtering caps isn't particularly high, since GW uses 85°C bulk caps and many Elite EJ filtering caps on the secondary side. We'd really prefer to see only good Teapo electrolytics instead of those Elites. Thankfully, a number of polymer caps also handle ripple filtering, and they should last a lot longer.

A half-bridge topology is implemented on the primary side, along with an LLC resonant converter. On the secondary side, we find a synchronous rectification (SR) design along with a pair of DC-DC converters for generating the minor rails. The heat sinks are quite large for a Gold-certified PSU, and the many power cables running freely over the secondary side surely block airflow to the electrolytic filtering caps. The polymer caps, on the other hand, which can withstand much higher operating temperatures, are in clear view.

A small PCB holds the AC receptacle, the power switch, one X cap, and two Y caps. The EMI filter continues as usual on the main PCB with two CM chokes, one X cap, and a pair of Y ones. Great Wall apparently decided that an MOV (Metal Oxide Varistor) wasn't necessary. This is a great shame since MOVs protect the PSU and your other components from spikes and surges coming from the mains network.

An NTC thermistor and bypass relay form the inrush current protection circuit.

Two bridge rectifiers (GBU1508) fully rectify the AC voltage. Combined, they can handle up to 30A of current.

A pair of Vishay SIHG33N60E FETs are used in the APFC converter, along with a single CREE C3D08060A boost diode. The bulk (smoothing) caps are provided by Rubycon (400V, 390uF each or 780uF combined, 85°C, USG series). Although that's one of the best capacitor manufacturers, we want to see bulk caps rated for higher temperatures, even if they come from a lesser manufacturer.

In the APFC control section we find a Champion CM6500, along with a CM03AX Green PFC controller. Both are installed on the solder side of the main PCB.


Two Fairchild FCH104N60F FETs are the main switchers, configured in a half-bridge topology.

The LLC resonant controller is a Champion CM6901X, which operates the main switchers in PWM mode under light loads and switches to FM mode at higher loads. The controller is installed on the mainboard's solder side.

The secondary heat sink hosts four A-Power BV6N19 FETs responsible for regulating the +12V rail. On the same heat sink, a PFR30L45CT SBR (Schottky Barrier Diode) is installed to handle the 5VSB rail. The standby PWM controller is a TinySwitch-III TNY278PN.

Both VRMs that regulate the minor rails are hosted on the same PCB. Each one uses two AP0403GH FETs to regulate its output, and the common PWM controller is an Anpec APW7159A. Two FPCAP polymer caps are installed on the VRM's PCB. These are used for filtering the minor rails.

Most electrolytic filtering caps on the secondary side are provided by Elite and belong to its not-so-good EJ family. We also find several Teapo SY caps, two CapXons caps, and a single Chemi-Con (KY) capacitor. All of the electrolytics on the secondary side are rated at 105°C. Some Chemi-Con polymer caps also filter the +12V rail, and those are a nice surprise since they'll likely alleviate some of the burden from lesser-quality capacitors.

The modular board hosts four polymer caps: two CapXons and two Elites. They're used for ripple filtering purposes.

A Sitronix ST9S429-PQ14 serves as the protections IC, and it's installed on the main PCB. This is a rebadged Unisonic Technologies S3515 without over-temperature protection support, so OTP is implemented with the fan control circuit's help. A thermistor attached to the secondary heat sink is responsible for feeding temperature information. Should the internal temperature climb too high, one of the supervisor IC's protections is triggered, effectively shutting the PSU down. We tested this with our trusty heat gun, and indeed the PSU switches off when the secondary heat sink's temperature climbs above 115°C. An AS358 dual op-amp is also tied into the protection features; it's installed on the main PCB's solder side.

The soldering quality is decent for this price category, and we didn't spot any extra-long component leads waiting to cause a short.

The HA1425L12F-Z cooling fan is provided by Hong Hua (140mm, 12V, 0.22A, 1800 RPM). It's a mainstream model with a sleeve bearing. That means it's quieter than a fan with the same specs and ball bearings, but it won't last as long. Riotoro's fan profile is relaxed enough to maintain low rotational speeds under normal conditions.

While we wouldn't want to guarantee a power supply for five years if it had a sleeve-bearing fan in it, remember that Corsair did upgrade the CS850M's warranty coverage to five years as well, and that PSU is based on the same platform. Then again, we're told Corsair switched to a rifle-bearing fan at the same time.

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16 comments
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  • Pompompaihn
    Enigma is a HORRIBLE name for the one part in your computer you want to always work exactly as specified and never outside of those specs....
  • gdmaclew
    All I want to know is...Tier 1, Tier 2, Tier 3 or Tier 4?
  • zthomas
    850 will power a normal system.. but thinking VR or a second video card.. 850 ain't enough.. I just upgraded from a 700 to a 1200.. why go small, go larger.. you run a 900 series.. you want a punch.. not a lag..
  • maxwellmelon
    A mov can be a blessing and a curse. When the MOV eventually fails it offers no protection (and there is no indicator on it to indicate failure) then after awhile it will form into a short at which point the psu will fail to work due to a short on the incoming mains. so your MOV will can extend the life by protecting the psu. but in the end it will be the end of the psu. In a lot of ways it is still better to get a good surge protector with MOV protection inside of it because they actually have an indicator to let you know the MOV has failed and you can actually replace the surge protector..If the MOV has failed in the psu you will never know and even if you did know the whole PSU has to be replaced. a good surge protector is still cheaper to replace then the psu.
  • anbello262
    1415492 said:
    850 will power a normal system.. but thinking VR or a second video card.. 850 ain't enough.. I just upgraded from a 700 to a 1200.. why go small, go larger.. you run a 900 series.. you want a punch.. not a lag..


    I actually don't agree with you at all. 850w is enough for almost any system with even 1080 SLI, and VR doesn't actually require more power by itself (only requires power by high utilization of your system).
    So for almost anyone, 650w is more than enough even for high end systems, and if you want to SLI high end cards, then 850W is advisable.
    More than that is overkill in almost all cases, in my (somewhat informed) opinion.

    Having a good quality PSU is a lot more important than having more than 850W. And quality PSUs with more power tend to be a lot more expensive than a very good 850w one, from my experience.
  • Aris_Mp
    you are right about the MOV, however personally I prefer a PSU featuring a MOV along with a UPS and a surge arrester combination. Moreover, for users that don't use surge arresters etc a MOV can save their systems besides the PSU and this is why it must be used always.
  • jonnyguru
    141101 said:
    All I want to know is...Tier 1, Tier 2, Tier 3 or Tier 4?


    If that's not a joke, then you sir do not need to be here... let alone building PCs.
  • anbello262
    112719 said:
    141101 said:
    All I want to know is...Tier 1, Tier 2, Tier 3 or Tier 4?
    If that's not a joke, then you sir do not need to be here... let alone building PCs.


    Actually, having the PSUs ordered in quality tiers is a very handy way to recommend PSUs, and therefore, for the people who are not so technically proficient with the electronics inside a PSU and specific meanings of the tests, knowing if this is a "Great, good or garbage" PSU is the only important part.

    Yes, there is more information to be had by reading the whole review, but only for those who understand it (which is by no means necessary, in order to be a very good system builder). Having a qualified person tell you "this is a safe and recommended unit for system builders / this is good enough for the price / don't buy this!" is extremely useful for the whole community.
  • Robert Cook
    If nothing else it is more competition, and a pretty promising start at that.
    A solid review.
    <Rant>
    Now on other news, PLEASE stop those damn auto play videos embedded in articles! My main system might be fine with them, but my laptop is from 2009, and it was not high spec even then. These videos are a major drain, and now there are ads before hand which means I cannot even hit the X option until the ad has played. (So I am loading free ad revenue for you at the cost of my precious little RAM.)

    Annoying clickbait is one thing, I can scroll past it, but these auto play ads/videos follow me down the page... :(

    I have been a member here for over two years and I am by no means going to stop, but I would like to be able to read articles (especially well done articles on this site) with out having great difficulty even scrolling down a page.
    </Rant>
  • Robert Cook
    Also I do not even use adblock so you are already getting ad revenue. (I respect your right to advertise, but force playing a video and then adding ads seems a bit over blown.)
  • zthomas
    1846741 said:
    Also I do not even use adblock so you are already getting ad revenue. (I respect your right to advertise, but force playing a video and then adding ads seems a bit over blown.)


    sounds to me you could use adblock.. its free.. will stop all those annoying adds and popups..
  • Karadjgne
    CS850 is $120, this unit is $110. That's going to be a hard sell when faced by brand recognition. Never heard of the brand, assume it's junk or it would be known, buy what I've heard of. What's going toake it harder is sli builds using high end gpus are expensive, builders will go with a reputable psu, Evga, Seasonic, Corsair for 850w. Doubt someone who can afford twin 1080's will be even tempted to look at this unit. Which leaves the ppl who have 2 hdds so need to have more power and a gtx1060, so 850w just to be safe crowd.
    I think Riotoro should have taken the shorter route, like the CX 430 did, and blown the doors off the 400/450w market at $10 cheaper than the CXM 450
  • WhyAreYou
    Looks nice actually, good review
  • amk-aka-Phantom
    1426528 said:
    I actually don't agree with you at all. 850w is enough for almost any system with even 1080 SLI, and VR doesn't actually require more power by itself (only requires power by high utilization of your system). So for almost anyone, 650w is more than enough even for high end systems, and if you want to SLI high end cards, then 850W is advisable. More than that is overkill in almost all cases, in my (somewhat informed) opinion.


    Agreed completely. I have a single GTX 970 with a Core i7-2600 (still kicking!) and I almost managed to run it off a 400 W Seasonic PSU (I normally use a 750 W that I bought a long time ago planning to SLI two 560 Ti). Almost - because *once* in a while I'd get power-related BSODs in Overwatch. But I bet a 450 W would manage it just fine. People's obsession with higher-wattage PSUs is unjustified, and to those who say "why not" - BUDGET!
  • Karadjgne
    Can't blame ppl for wanting bigger. Yes, you probably could squeeze in a i7-2600 and gtx970 on a 450w, I know it's been done before. But running that close to maximum output by the psu for any length of time does have its own quirks. First, there's no guarantee that any particular buyer is going to get a high quality, tier 1 or tier 2 psu that'll withstand that abuse, many opt for more budget oriented tier 3 mediocre units. So quality power outputs, ripple suppression etc is dubious at best at closer to 100% loads. Second is the best efficiency, power to heat ratios, power cleanliness, fan noise, etc. is found in the 50% to 70% range. This is why any system running a gtx970 should be at a minimum of 520-550w. Third, there are no quality 500,600,700w units. None. For any quality unit you are looking at 450,520,550,620,650,750w units. So again, 520-550w is perfect for a 970. Forth is OC. This varies per user, personally my 3570k is at 4.3GHz and it's gtx660ti is max OC on a Seasonic M12-II 520w. My 3770k is currently at 4.6GHz (was 4.9GHz) and its gtx970 is max OC on a Evga G2 550w. Neither is overkill powered, but both are quality units designed to handle whatever I can throw at them and still come out smiling.

    There's only one hard and fast rule of psus. Don't skimp. Be surprised how many people try and cheat that, only to end up with power related issues.
  • anbello262
    1011591 said:
    First, there's no guarantee that any particular buyer is going to get a high quality, tier 1 or tier 2 psu that'll withstand that abuse


    That's exactly the reason I said that, for a given budget, Quality is a lot more important than Capacity. Usually it's a lot better to have a 550W top quality one for a than a 750W cheap/mediocre one, for example. And almost in every single case where lots of power are necessary, it's better to get a top quality 850W than a mediocre 1200W (as someone above suggested).


    1011591 said:
    There's only one hard and fast rule of psus. Don't skimp. Be surprised how many people try and cheat that, only to end up with power related issues.


    I completely agree with this. It was common that most games will not tax both cpu and gpu to their max power consumption numbers for long periods of time, but that is no longer the case with Overwatch and some other apps, and therefore a lot of people who skimped on their psu are having issues now.

    But I also think that it is quite unwise to go to the other extreme. Buying a 1200W top quality unit when you would only need 750/850W would be an unnecessary waste of money for almost all builders.