Hiper HPU-3S350

Every feature of this product speaks out its belonging to the low price range – the plain gray case, the thick punched grid of the fan, the short cables. However, the manufacturer declares a high enough wattage of 350W (330W without the negative polarity sources and the standby source).

The interior doesn’t bring any surprises. This is just a typical inexpensive PSU. The regulator is based on the TL494CN; the capacitors of the high-voltage rectifier on the PSU’s input are 680µF each; the line filter and the rest of the components are all present here. Two things are disturbing, though. I mean the very thin heatsinks which are, however, excusable in a cheap PSU (if it normally holds the load, that is) and the overall sloppiness of assembly – the components that rise above the PCB (capacitors and coils and others) stick out irregularly to all sides, leaning at different angles.

The PSU is equipped with a passive PFC device. You can’t see it in the snapshot above as it is attached to the removed cover of the case, but you do see the thick wires that go to it. Note also the heatsink-attached card that controls the fan speed.

The cables are few:

• A 36cm mainboard cable with a 20-pin connector
• A 38cm ATX12V cable with a 4-pin connector
• A 38cm cable with one SATA power connector
• Two cables with three Molex connectors and one mini-plug on each (38cm from the PSU to the first plug and then 15cm more to each next connector)

Moreover, all the cables have a 20AWG section which is too thin for a 350W PSU. The 18AWG section is more common, especially since there’s a high enough specified current on the +12V rail (but there is a 16A F16C20 diode pack installed in the +12V rail).

The specification of this PSU falls a little short of the ATX12V 2.0 standard. The maximum load on the +12V rail is just 4W smaller than is required from the typical 300W ATX12V 2.0-compliant power supply, and the mainboard’s connector is 20-pin, too. The allowable load on the +5V and +3.3V rails is, on the contrary, closer to the earlier versions of the standard in which it was higher. Thus, the Hiper HPU-3S350 appears to be a kind of transitional product.

The cross-load characteristic of this PSU looks bad. None of the three output voltages is really stable. The +12V, so very important for modern computer systems, easily goes the whole way from the minimum to the maximum, depending on the +5V load, and the +5V voltage itself is in fact too high initially.

Constructing the cross-load diagram is the first item in our test program. It is then followed by checking the stability of the power supply under load and measuring the speed of the fan(s). Unlike building the cross-load diagram which takes only 15-20 minutes, such tests require the power supply to work for quite long at various loads, including the highest. The whole test session may take as long as a few hours of constant operation.