Power Supply Review / Teardown | 700W Modular FLEX Power Supply from TaoBao 7760B (MF-700F)

REVOCCASES

Shrink Ray Wielder
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Update: OVERTEK now offers the original ENHANCE 7660B pre-modded with a Noctua fan for a reasonable price and full warranty. I would probably go for that one instead of the TaoBao 7760B.

Update 2: there seems to be a new revision of the MF-700F being sold with totally different modular cables / connectors


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I needed a new FLEX power supply for my RCC-SMALL2 project and I know some of you are also looking for alternatives to the famous ENHANCE 7660B.

Some time ago I spotted a promising new FLEX PSU on TaoBao which is supposed to deliver up to 700W. The manufacturer is a Chinese Company called "Extreme Cat Electronics" (极致猫电子) and they are already in the business for some time. The company is mainly doing OEM, so their PSUs sell under different names / brands. The one I got sells as MF-700F but some sellers like YTC also just call it 7760B.

So let's have a look what we can get for CNY 700,- (ca. USD 110,-) ...

the PSU comes with modular soft white cables, which should fit for most builds



the manufacturer claims 700W max output and 90+ efficiency so let's have look what's inside...



I am pleasantly surprised that they use quite good brand components and nothing "no-name" like many other TaoBao FLEX PSUs I have seen before. Overall I think the price of ~110 USD is fair, I wouldn't pay more though. The small heatsink is a good indicator that it has a decent efficiency. I am not so happy that the screw locking washer for the grounding wire is missing. Normally that is mandatory if they want to get a CE certificate so I doubt the CE they printed on the label is legit.

Just FYI, below is the "METALFISH 500W FLEX" PSU for comparison. Guess even if you have no idea about power supplies you can tell that there is a big quality difference.



The side view reveals an SRC/LLC+SR Controller which is another indicator that it really has 90+ efficiency.



Some things that should be improved IMO: one of the smaller caps is touching a solder spot and the wires from one of the buck chokes are touching a screw on this heatsink there. Although that this seems to be no issue I would feel more comfortable having some insulation or creepage distance there.



soldering quality looks clean, not too much tin and no cold solder spots



fan / noise: I could not find any datasheet for the fan they are using but it seems to be a 9000RPM one which sounds like a jet engine at full RPM. The fan is silent in idle but starts to make a high pitched unpleasant sound when going over 200W. It is controlled by the output load, not by temperature so keep that in mind if you want to do a fan swap. Update: the fan is temperature controlled and will ramp up from 20% @ 30C to 100% @ 60C. At full load, that tiny fan needs to get rid of ~75W heat and a Noctua 5000RPM fan just can not do that. I haven't tested it yet but I would guess you should be OK with a Noctua fan up to 400W load.



for PSUs it's important that materials used are UL approved / flame retardant so I am glad to see that the insulating materials do not burn



if you are interested, the manufacturer "Extreme Cat" also did some own videos showing the performance and internals of his PSUs, thanks @tinyitx for sharing

An opening up of the 7760B, showing the internal:-
https://www.bilibili.com/video/av839938555/
Stress test of the 7760B:-
https://www.bilibili.com/video/BV1oZ4y1V73m


I'll post an update here once I did a a fan swap and tested the PSU for some time.

My thoughts so far:

this one is probably the best Chinese TaoBao FLEX PSU I have checked so far but is it worth to buy? Well, consider this...
  • VELKA is selling the original ENHANCE 7660B for USD 160,-
  • The MF-700F sells for 700,- CNY (ca. 110,- USD) on TaoBao plus you have to use Superbuy and pay a lot for shipping, perhaps also customs / import fees
  • If there are quality issues, you would have to return it to China on your own cost and waiting a long time to get it repaired / replaced
  • unless it has to be black and modular, modded second hand 500W ~ 600W FLEX server PSUs are much cheaper and also do the job

to be continued....
 
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REVOCCASES

Shrink Ray Wielder
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first test with a Noctua fan swap looks promising.

only had a NF-A4x10 on hand so I used some adapters to make it fit (note: I made the fan intake, usually it is exhaust)



after 30 minutes load testing @ 300W I measured about 60C peak and it is finally silent



of course it will get hotter once the PSU sits inside your case but I guess with a NF-A4x20 you should be fine up to 400W load (if your case is well ventilated / the PSU has access to fresh air). I'll try to get one of those and repeat the test then.
 
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ezerez

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thx for the review, was also looking into some alternatives for flexatx psu, looks like a good option. Just a small comment on your comparison for the enhance from velkase. You also have to add shipping there (49.99 for germany) + guaranteed taxes and import on that amount.
 
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Shrink Ray Wielder
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Just a small comment on your comparison for the enhance from velkase. You also have to add shipping there (49.99 for germany) + guaranteed taxes and import on that amount.

Sure, always have to consider where you are living. For US customers I guess the ENHANCE might be the overall better choice. For European customers the situation looks different.
 
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Shrink Ray Wielder
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I did a few more tests with a 4020 / 5000RPM fan today. It's not a Noctua but has similar airflow characteristics.

I also have to correct my original post: the fan is temperature controlled. Here is my "guestimate" how the fan curve looks like:



I'm not sure where / how they measure the temperature but IMO the most important area is near the caps as they are the most heat-senitive part inside your PSU. As hotter the caps get, the sooner they will fail (see example below). So I placed a temperature probe in this area.





1st test: 30 minutes 300W load / 4020, 5000RPM fan / Exhaust (standard orientation)



2nd test: 30 minutes 300W load / 4020, 5000RPM fan / Intake



Interesting results. With the fan in standard orientation (exhaust) the internals of the PSU seem to get much hotter. So why is the fan on most FLEX PSUs exhaust? Honestly, I have no idea. I work a lot with industrial power supplies and most of them have the fan set as intake, pushing fresh air inside the PSU. For FLEX maybe they do it because of dust, fan turbulence (noise) or to prevent additional hot air is pushed in your PC... Anyways, guess they have a reason to do so.
 
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REVOCCASES

Shrink Ray Wielder
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Flex is a server standard and being exhaust has the airflow in line with the rest of the airflow inside the rack. PSUs that have the fan on the opposite side are always intake for the same reason.

Makes sense.

However, I think for our SFF cases it might be sometimes better to flip the fan. For example when I had the Metalfish S3, my old FLEX would run much cooler and less noisy when I had the fan set as intake. Think I will test it like that for a few days.

PS: There are some custom FLEX sized PSUs (e.g. made for HP, DELL, or here my Subor Z+) which have the fan as intake. But yeah, those are custom, not "standard FLEX".

 

robbee

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PS: There are some custom FLEX sized PSUs (e.g. made for HP, DELL, or here my Subor Z+) which have the fan as intake. But yeah, those are custom, not "standard FLEX".

Yeah, and I think this emphasises your point: flipping the fan will benefit you when using flex outside of a rack setup since even system builders do it.
 

tinyitx

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I think, one can order this PSU simultaneously with the Noctua fan mod. This might be a good choice as one then does not have to open the unit (thus voiding the warranty).

Also, the pic below shows probably a typical server rack, housing a flex PSU. Note the typical front-in-rear-out airflow.
 
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Shrink Ray Wielder
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So, as I read it the 7706B is still a better option?

IMO the ENHANCE ENP 7660B is probably the best FLEX PSU available. If you are looking for quality and reliability, I would go for that one.

The one from "Extreme Cat" I showed you here is "inspired" by the ENHANCE design, they just use cheaper components where possible to realize a lower price and made it modular. Also I have no idea how reliable it is in the long run. But it is certainly much better than something like the MetalFish 500W FLEX.
 
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Ahlix

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I'm still conflicted if it's worth the money for Black and Modular, two things I really want in my build lol.
 

scatterforce

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@REVOCCASES Could you show off or explain the wiring harness for this exact model? Does it still daisy chain the 2 PCIE 6+2 connectors with 3 12volt wires?

If yes, then there really is no benefit for that 700W rating. You can't safely draw more power for a 3080/3090. It would be better to use the ENP 7660B from Velka with the wires soldered to the PSU.

Anyway, great work!
 

REVOCCASES

Shrink Ray Wielder
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@REVOCCASES Could you show off or explain the wiring harness for this exact model? Does it still daisy chain the 2 PCIE 6+2 connectors with 3 12volt wires?

If yes, then there really is no benefit for that 700W rating. You can't safely draw more power for a 3080/3090. It would be better to use the ENP 7660B from Velka with the wires soldered to the PSU.

Anyway, great work!

It's four +12V wires and four GND. So theoretically, if they use good connectors and thick enough wires you should be OK. But good point. I still wanted to do a load test to check the quality of cables, connectors and actual output but my load tester broke.

If you want to run a 3080, I would also be more comfortable with a non-modular FLEX like the 7660B. A 3090 I wouldn't even run with that one to be honest.
 
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scatterforce

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It's four +12V wires and four GND. But good point. I still wanted to do a load test to check the cables, connectors and actual output but my load tester broke.

If you want to run a 3080, I would also be more comfortable with a non-modular FLEX like the 7660B. A 3090 I wouldn't even run with that one to be honest.
Thanks for the quick reply. I have neither a 3080 nor 3090 (obviously, given current world conditions) but I'm planning for future builds.

Your post convinced me to get the 7660B and not this 700w model.
 

REVOCCASES

Shrink Ray Wielder
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Probably can't go wrong with the ENHANCE 7660B when you need a good high power FLEX PSU. I heard it also won't get too noisy up to 420W, even with the stock fan.

For my build I actually only need about 350W max. so the TaoBao 7760B seemed to be a good choice. At 40 to 60% load it has the highest efficiency and runs relatively cool and quiet with a Noctua fan swap.
 
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tinyitx

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It seems the most common complaint of the Enhance 7660B is its fan noise (thus, the Noctua fan mod). The next most common probably is the possibility of coil whine. Perhaps this is common enough that this 'Extreme Cat' version of 7660B says it has improved in this aspect. I have no personal experience but, from reading some users reports, it seems the coil whine is, indeed, eliminated/reduced. How true this is, I do not know. So, if one is very susceptible to coil whine, one has to really decide to choose between the Enhance version (known brand) and this 'Extreme Cat' version (less known).
 
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Shrink Ray Wielder
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My Extreme Cat does have very slight coil whine, but my R9 Nano whines way louder, so that's OK for me 😅 the stock fan is a bit annoying though.

Concerning the Noctua fan swap I would keep in mind that both PSUs seem to come with a 9000 - 10000RPM fan and you'll need that airflow to keep them cool enough under higher load (400W+), especially if they sit in a "hot case".

Using a Noctua will make is less noisy but also reduce the max. output rating and/or can decrease the expected lifetime of your PSU.

 

ezerez

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