I've seen a lot of hype about active PFC in PSUs - mainly how it improves energy efficiency (it doesn't make a significant difference, and may actually lower efficiency) and how it saves money. PFC may or may not save you money; it depends very much on your electricity supply contract and the policies of the electricity suppliers and/or government in your country. For example, in the UK domestic electricity meters must legally ignore powerfactor. Large consumers (e.g. big office developments and factories) may be billed for low power factor. If you are operating servers at a co-location site, then you may pay heavily for power factor (as generators and UPSs may need to be oversized).
I've even seen 'silent' PSUs - equipped with massive heatsinks and exotic cooling schemes, but still compromising with a low power-capacity to prevent overheating.
What all these PSUs have in common is relatively poor energy efficiency (about 70%). In fact, some manufacturers have had the cheek to introduce their 'active PFC' series with claims of high efficiency - yet their 'active PFC' series PSUs actually have lower energy efficiency than their conventional supplies (as low as 65% - the minimum allowable under the ATX specification).
Higher energy efficiency in the PSU would bring with it advantages - tangible lower energy consumption and costs for all customers and reduced heat output. This may bring secondary benefits of reduced weight and noise. A modern high-end enthusiast PC might need as much as 150W of clean DC power - a 70% efficient PSU will need 215W from the wall while producing 65W pf heat, making the PSU the biggest single source of heat after the CPU.
High efficiency is not particularly difficult, although it is potentially costly. Laptop power bricks routinely get over 80% efficiency. I've seen some brick supplies over 90%, and a couple that have claimed 93%. With the use of premium semiconductors and magnetics, together with sophisticated designs (e.g. full bridge switching and synchronous switched rectifiers) I am sure that better efficiencies could be achieved.
Even replacing a conventional supply with one offering 85% efficiency brings tangible benefits. The system above with a 85% eff PSU would only draw 176W from the wall, a saving of 39W bringing cost savings of $10 a year for a home/office PC (left on about 8-10 hours a day) - and much, much more for a co-lo server.
I've even seen 'silent' PSUs - equipped with massive heatsinks and exotic cooling schemes, but still compromising with a low power-capacity to prevent overheating.
What all these PSUs have in common is relatively poor energy efficiency (about 70%). In fact, some manufacturers have had the cheek to introduce their 'active PFC' series with claims of high efficiency - yet their 'active PFC' series PSUs actually have lower energy efficiency than their conventional supplies (as low as 65% - the minimum allowable under the ATX specification).
Higher energy efficiency in the PSU would bring with it advantages - tangible lower energy consumption and costs for all customers and reduced heat output. This may bring secondary benefits of reduced weight and noise. A modern high-end enthusiast PC might need as much as 150W of clean DC power - a 70% efficient PSU will need 215W from the wall while producing 65W pf heat, making the PSU the biggest single source of heat after the CPU.
High efficiency is not particularly difficult, although it is potentially costly. Laptop power bricks routinely get over 80% efficiency. I've seen some brick supplies over 90%, and a couple that have claimed 93%. With the use of premium semiconductors and magnetics, together with sophisticated designs (e.g. full bridge switching and synchronous switched rectifiers) I am sure that better efficiencies could be achieved.
Even replacing a conventional supply with one offering 85% efficiency brings tangible benefits. The system above with a 85% eff PSU would only draw 176W from the wall, a saving of 39W bringing cost savings of $10 a year for a home/office PC (left on about 8-10 hours a day) - and much, much more for a co-lo server.