However, we’ve got more frightening numbers when measured power consumption of the systems in idle mode. Even the Core 2 Quad platform consumed as much as 300W at that! Alas, while the manufacturers of CPUs have taken to reducing power consumption of their products, the makers of chipsets and graphics cards have, on the contrary, relaxed. One GeForce 8800 GTX consumes as much as 70W when idle and we’ve got two of them in our system. 140 watts for the graphics subsystem alone that is displaying an empty Windows Desktop – that’s too much, to my mind.
And finally, to measure power consumption of a typical home PC we assembled a system with a Core 2 Duo X6800 (running at its default clock rate) and with one GeForce 8800 GTX. This PC was easily powered by a 420W PSU from HEC Group and our measurements showed that it consumed only 280W under 3DMark06. This is not a big number, considering that 300W PSUs are currently regarded as low-wattage products.
It is a widespread opinion that you should buy a PSU with higher wattage than you actually need as a kind of reserve for the future. This opinion is questionable. To begin with, such a PSU may prove much noisier at work than models with lower wattage. And second, when you do need its full wattage, if ever, the selection of connectors may have changed once again, and you’ll have to use a lot of adapters in your PSU. I can remind you the recent innovations: a 24-pin mainboard power connector, 8-pin power connectors for CPUs, SATA power connectors, 6-pin connectors for graphics cards. Yes, you can power all these components with an older PSU via adapters, but adapters are no good in terms of reliability and the ease of assembly.
Anyway, now that the manufacturers have got to producing 1000W and higher power supplies, our job is to test them and report the results to you. And it’s up to you to decide if you need such a PSU at all.
To load the PSUs fully we had to revise our testbed and install larger heatsinks and more powerful fans (Jamicon, 120x120x38mm, 2800rpm) on the load transistors of the +12V channels:
In the bottom part of the photograph you can see a small (80x80x25mm) fan on the heatsink placed on the load for the +5V and +3.3V channels (up to 250W combined). At the top there are two giants capable of loading the +12V power rail of any PSU up to 880W.
Before getting to the PSUs proper, I want to tell you about the new connector that is meant to replace or add to the customary 6-pin graphics card connector:
This is a 12V power connector as before, but with two more pins. It resembles the 8-pin CPU connector installed on some mainboards, but is not compatible with it electrically as well as mechanically (in other words, you cannot plug one into another). Anyway, the PSU manufacturers often label this connector as “PCI-E” to avoid confusion.