First review, please forgive for anything done wrong.
I've just recently picked up half a dozen of these EZcool "Super Silent" 500W power supplies, mainly because they were one of the cheapest supplies (Around $50AU, approx $40US) while still offering a decent wattage, and not being totally bargain basement, and part of my buisiness being PC repair we tend to go through quiet a lot.
This review is based on a mid level computer, with a Intel 6600 Dual Core, 2GB ram, and a fanless Gigabyte 7600GS.
The first thing I noticed when opening the box was the attractive gun-metal finish, catagorised as the "Black" model, which combined with a decent weight, giving a feel of quality well above the asking price. While not being nearly as hefty as say a Antec Phantom, it feels quiet solid.
An interesting part of the design is a clear plastic cover on the exhaust (top) side of the 120mm fan, blocking off the back (grill) half. There is about a 10mm gap between the fan and the plastic. The cover not only seems to duct air towards the front of the unit, but also cover up the top of mmost of the heatsink fins, assumedly for the purposes of laminar flow and minimizing turbulence.
Cabling provided is a standard 20/24pin ATX plug, with sleeved cabling, 2 12v accessory cables, each with 3 standard 4pin plugs and 1 floppy drive plug. There is only one SATA power plug, and one (4-pin) P4 connector with a conversion cable to plug into a single 6 pin AUX connector, so would be unsuitable for a SLI board requiring dual AUX connections. It is not specified whether the 12v rails are shared or independant, so I would not reccommend this for owners of top end video cards which require inpedendant 12v rails.
The PSU comes with all the standard features, such as over voltage/current, over loading and short circuit protection on the 3.3, 5 and 12v rails. It is also badged with an optional "PFC Technology", which is claimed "save 40% power usage", however I could not find any more details on what this involves. It has a automatic 3 speed thermostatic fan controller.
Starting the PSU by earthing the power on (purple) line, I was immediatly surprised by how quiet the PSU actually was. Branding with a "<20dB" I think is quiet justified, at least when on the lowest fan speed. In our reasonably quiet office, it was completely inaudable further than around 15cm, at which point a quiet woosh, and a slow low pitched ticking was just audible. When under load, there is also a low buzzing audable at the same distance, however inside a case these would both be below ambient, and the noise quality was, I felt, quiet similar to that of the Scythe Kama Flow SA1225FDB12L @ 7v, only a slower ticking. The fan appears to run at quiet a low RPM, I would estimate, based the ticking compared with the table of the Scythe Kama, a RPM of around 500 to 800 at the most. There was very low airflow at the lowest speed.
In the testing rig I had, with case temperature up to around 32 degrees C, and, I would estimate, up to about 300W power usage, the fan did not audibly speed up, so I cannot say what difference the 3 different fan speeds would make, however with a well ventialted case I don't think this would be a problem.
Voltage regulation seemed good, with less than 5% variation under load on all rails. There did not seem to be much variance between the 3 units I tested.
In addition, having talked to our wholesaler, I have been told that, as of yet, they have had zero of these power supllies returned faulty, while they have several each week of the marginally cheaper OEM PSUs reurned.
All in all, for a cheap, quiet power supply, I haven't seen anything which is on par with EZcool's offerings, and while I have no experience with the 700W model I can only assume similar results. For only $10 more than the base OEM power supplies, it makes a great choice for a quiet computer on a budget.