X-bit labs

ATX Power Supply Units Roundup. Part V (page 14)

Category: Other

by Oleg Artamonov

[ 11/21/2006 | 03:51 PM ]

Corsair CMPSU-620HX (620W)

I can’t definitely tell you what connection exists between memory modules and power supplies, but it is a fact that the module manufacturers have begun to roll out PSUs under their brands, too. I’ve already tested PSUs from OCZ (and will return to them later on in this review), and here is a model from Corsair Memory.

Of course, Corsair is not the actual manufacturer of the PSU. The product is made by Seasonic. The CMPSU-620HX is an intermediary variant between Seasonic’s S-12 and M-12 models. It doesn’t have a second fan (like the M-12 does), but has detachable cables (unlike the S-12).

The innards of this power supply look quite normal to me. There is no reason for the engineers to change the well-established component layout. The only exception is that the high-voltage capacitor, usually located near the left edge of the case, has moved to the center of the PSU whereas the left part is all occupied by an active PFC device, the rectifier’s diode bridge and a line filter.

There is a card with connectors for detachable cables on the rear panel. The soldering is very neat and tidy there.

The PSU uses rather simple heatsinks punched out of an aluminum bar. This may not sound good to some users because many hardware reviewers like to measure the dimensions of heatsinks, transformers and other components. There’s nothing wrong in that, however. The simpler heatsink provides less resistance to the stream of air, so the airflow will be stronger with a same-static-pressure fan (as you know, each fan has not one but two basic parameters: performance describes its ability to work in an open environment whereas static pressure describes its ability to drive a stream of air through an obstacle). As a result, the cooling may prove to be better with smaller heatsinks than with larger ones.

The same goes for the dimensions of the transformers and chokes. They depend on the PSU’s operating frequency (the higher the frequency, the smaller the components, the PSU wattage being the same) and topology. Having a PWM frequency of about 130 kHz and a double-forward topology, the ferrites in the CMPSU-620HX are just the necessary size for normal operation at full power, although they seem small in comparison with older same-wattage PSUs that used to have a half-bridge topology and an operating frequency of 70 kHz.

The PSU is equipped with the following cables and connectors:

• Mainboard cable with a 20+4 connector (52cm long)
• CPU cable with a 4-pin connector (53cm)
• CPU cable with an 8-pin connector (52cm)
• Two 6-pin connectors for graphics card cables
• Five 5-pin connectors for power cables of PATA and SATA drives (there’s no difference between the PATA and SATA cables – you can plug any of them into any PSU connector)

The following is enclosed with the PSU:

• Two graphics card cables with 6-pin connectors (55cm each)
• Two cables with three Molex connectors on each (50cm+15cm+15cm)
• Two cables with three Molex connectors on each (30cm+15cm+15cm)
• Two cables with three SATA power connectors on each (50cm+15cm+15cm)
• One cable with two SATA power connectors (50cm+15cm)
• Adapter from one Molex connector to two floppy mini-plugs
• Adapter from one Molex connector to two fan connectors (designed like Molex, but with +12V voltage only)

The PSU is declared to have three +12V lines with a max combined current of 50A and a limitation of 18A on each line. However, the PSU manual informs that the lines are united into one when the limitation is exceeded. In other words, there is no actual division of the lines inside the PSU, but the user has already got used to the idea that there must be several 12V outputs, so the manufacturer couldn’t but specify several such lines on the PSU label. Of course, the lack of a “virtual” splitting of the +12V power rail into several output lines has no effect at all on the PSU’s voltage stability or output power.