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This review is from: LOGISYS Computer PS550AC 550Watts ATX12V Power Supply
Pros: Efficient 5VSB rail
Cons: Where do I begin? First of all, there was a screw rattling around inside the case!!! No wonder these are giving people DOA's. This has got to be the worst build quality I've ever seen in a power supply. Also, you don't even get the unit pictured here. If you look at the pictures, that one actually has decent sized heatsinks, and looks more packed full of components. The one you get looks much more gutless, and the rear fan is actually sunk into the chassis of the unit. Speaking of the chassis, it wasn't put together correctly. The top and sides of the top cover are warped, and I could pull the rocker switch out of the unit with my bare hand because it was so loose.
I received a European power cord instead of a USA one.
"WITH FAN SENSOR CONTROL" That's just got to be a mean joke...Both fans run at full speed because they're wired straight to the 12V rail, and they are very, very loud. By the way, there's almost no lubrication in the sleeve bearings, don't except them to last long running at over 4,250RPM all the time.
There were many deep cuts and gouges on the solder side, and long component leads that were almost shorting out each other. It's amazing it powered on at all.
I thought the two input capacitors looked small for what they said, which is 1000µF. I pulled them and put them on my capacitance meter, and they read 524µF and 533µF. Wow!
One of the ground wires for the motherboard connector wasn't even soldered into the PCB.
Other Thoughts: Even if this thing was well built and put together, it still isn't close to a 550W power supply. Most modern computers uses about 90% of its load from the 12V rail. This unit is capable of about 20A on the 12V rail. That makes it about a 250W power supply. Do not buy this thing, for the sake of your computer, and the noise level in your room ;)
Don't buy this, because it will encourage them to keep building them like this. Tell everyone you know, avoid Logisys at all costs!
Pros: The PSU OEM is Solytech. This is a pretty decent power supply for the price. I would call it more of a 600W PSU, and I will list why. Even though it doesn't have APFC, at least it isn't half bridge. It uses double forward topology
First off, this thing has beefy primary silicon, good for up to 700W, two 1000µF 200V caps on the primary (voltage doubler, so 500µF usable, good for 700W)
Full input filter
Very nice fan
Good circuit protections
Cons: Inadequate heatsinks
low quality capacitors
Almost inadequate 12V rectifiers
The heatsinks for the silicon are on the small side for a 700W unit, which is why I don't recommend using this unit at full power.
Regarding the 12V rectifiers, it uses two 30A schottky rectifiers in parallel. This doesn't mean they're good for 60A total, as they are just in parallel. I'd guess together they could safely pump out about 50A, which is just below the 56A rating. It would help if they were TO-247 parts instead of TO-220. I'm saying this to be safe, as that heatsink probably gets very toasty around that amperage.
Other Thoughts: @ Anonymous. Don't be a moron. Just because it doesn't have PFC doesn't mean it can't handle fluctuations in the AC. That's what an input filter is for. Ever heard of that? All APFC does is correct the power factor, and make the input auto detecting. This unit has a better than average transient filter, with 4 Y caps, 2 X caps, 2 coils, 2 NTC thermistors in parallel, and 2 MOV's. This is plenty to filter spikes in the mains. And actually, I'll have to respectfully disagree about PFC reducing failure. PFC circuits are more complicated. I've seen many PSU's PFC circuit fail, usually the PFC booster coil shorts which blows the transistors, and then the fuse. If anything, it's more prone to failure. Input side failure is rare in non PFC PSU's, although more of the high quality manufacturers make APFC units. Obviously, there are plenty well made PFC units out there. Here in the US, no sort of PFC is required yet (PPFC or APFC)
This would be a great budget PSU for even a high end system. Just don't expect it to last forever.
This review is from: COOLMAX CX-400B 400W ATX v2.01 Power Supply
Pros: Coolmax has been "updating" this model of PSU, but mostly downgrading it further. It does have some pros though...barely.
It uses a nice quality fan, and even though it's wired straight to the 12V all the time (No thermal fan control whatsoever) it stays quiet, and the bearing has plenty of grease so it shouldn't fail.
The older revision of this PSU used the infamous two transistor circuit for the +5VSB, which wasted a lot of electricity and killed lots of motherboards. They updated it with an 8 pin IC to generate the +5VSB which is a lot more efficient and isn't prone to frying your motherboard.
Cons: Everything else... The old revision (Circa 2009) could pump out about 350W, this one is capable of about 275W (With a very mixed rail load).
It claims two 12V rails capable of 348W. HA! It only has one rail, and it uses a 16A ultra fast rectifier. Since the fan runs fast keeping it cool, I bet it could do the full 16A, but that's only 192W...Almost 90% of your computer uses the 12V. That makes this basically a 200W PSU in a modern system. And if you load it up, that 12V rail is going to sag quite a bit...
Other Thoughts: Don't give these guys your money, they don't deserve it.READ FULL REVIEW