What's up with Power Supplies?

Are all power supplies created equal?  Of course not.  But even worse, many people believe it is better to buy a cheaper "higher power" PS than a higher quality "lower power unit".  Tom's Hardware page produced a small article on power supplies here, and what goes into a cheap unit, but even that review provides some poor generic advice of looking for a higher power unit over a lower power unit.

When Dilithium import a PC chassis, we always include a high quality power supply.  The first chassis we imported included a 250W power supply.  At the time, 250W was on the high end of the available units, yet we accepted the slightly higher cost knowing it was in the interest of our customers, we also paid extra per unit for a high end 250W with temperature controlled features.  Showing the quality of this unit, we have found this Power Supply is even completely stable powering even a modern high end PC (Pentium IV 1.9GHz or Athlon XP1800+ with 7200rpm HDD, GF2-GTS, etc), even though on paper it doesn't meet the specified requirements.

When selecting a power supply for the AL3, we following a similar selection criteria.  We selected a unit which meets current Intel and AMD design requirements for stable system thermal performance, as well as a unit which provides abundant electrical power and meets all anticipated requirements.  Once again, this increased the cost of the units, but we feel the extra quality is worth it.

Below you will see a table detailing the different capabilities of a some real world power supplies (the 400W PSU had no distinguishable brand name).  Every power supply outputs a range of predetermined voltage levels, and the maximum current which that voltage level can supply.  The power rating of a power supply only provides the total maximum power supply capabilities,  it is a summary only, and is often misleading.  The true storey lies in the individual voltage/current capabilities.  Intel have defined its recommended minimum requirements for the Pentium IV CPU as well, which are detailed below.   The AL3 initially comes with either a Suntek 300W PSU Dual Fan PSU (details below) or a Apotheosis Honor 350W Dual Fan PSU (Details Below), (both provide dual fans which are required to conform to AMD and Intel's design guide for thermal management and power supplies).  The Debut comes with either a CW 250W PSU or a PowerWin Dual Fan 330W PSU as noted below.

As you can see, the higher quality 300W PSU actually outperforms the supposed 350W unit some cases, and the A/H 350W outperforms the 400W unit in many cases.  In one case, the JGE 350W PSU does not even meet the requirements set out by Intel, yet the 300W unit does.  Currents in blue detail the voltages in which the 300W & 330W unit exceeds that of the 350W PSU.  In all cases, the Suntek 300W unit meets or exceeds all of Intel's requirements.

The critical issue to note here, is that you can not simply judge a Power Supply by it's advertised wattage, which is only a guide.  Just as higher MHz in CPUs no longer means faster performance (eg Athlon vs Pentium IV), higher total wattage rating in a PSU does not mean more power where you need it.

Here endith the lesson.