Of course Murphy's Law is true and we always find something wrong after we publish reviews. There is definetely something wrong with the efficiency numbers from all our recent power supply reviews, either the built-in wattmeter in our load tester or our AC wattmeter is defective. We are investigating this right now in order to determine what is wrong and fix all reviews that may be affected by this problem. So far we also don't know which reviews were affected. We'll post a follow-up here as soon as we discover more. Thanks for the understanding.
4:50 PM PST Update: We discovered one transistor burned inside our load tester, which was biasing efficiency results. We also ordered a new wattmeter. We will redo all tests published recently, especially the one from Antec CP-850, as soon as the replacement transistor arrives. Sorry for this problem and thanks once again for the understanding.
06/17/2009 1:34 PM PST Update: Replaced the faulty transistor from our load tester and re-tested Antec CP-850. The results make sense now. I am now re-testing other power supplies to see if any other review was also affected by this problem.
06/17/2009 2:19 PM PST Update: Great news. Only the Antec CP-850 review was affected by this problem. I re-tested the power supplies we've reviewed recently and the results are just fine. Phew! At least some good news...
06/20/2009 1:09 AM PST Update: Due to the difference between the readings between the two power meters we have (Brand Electronics and Kill-a-Watt) as shown on Corsair HX850W review, I decided to buy a professional power meter, GWInstek GPM-8212R. This equipment is very expensive (USD 700) however it provides 0.2% precision and also allows to be calibrated via computer, so we can calibrate it from time to time to make sure that our equipment is 100% accurate. With the aquisition of this equipment we will be probably the reviewing website with the most accurate AC power and thus efficiency measurements on the web. I will keep you guys posted as soon as the equipment arrives.
06/23/2009 5:07 PM PST Update: The new power meter has arrived today. I've just updated our methodology, please take a look. I will try to update our recent reviews with the numbers collected by the new instrument.
