GT Omega Steering Wheel Stand
£99.98
Racing Wheel platform - optional G25/G27 Shifter Mount
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Antec High Current Gamer 620W PSU HCG-620M
Modular PSU with 620W Continuous Power
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ModMyToys 4-Pin to 5 Way 3-Pin Fan PCB
Superspeed Card reader internal / external connectors
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PSU
by Mikael Strand Introduction The aim of this guide is: • To explain the basic functions of a power supply • To explain the difference between the ATX 1.3 and the ATX 2.01/2.2 PSU standards. • To explain different PSU parameters and how these will make a difference to your system. • To help you choose the right size of PSU for your system and what to consider when purchasing a power supply. What does a PSU do? The main purpose of a power supply is to convert the 230V AC (110V in the US) electric supply that comes out of the wall socket into 3.3V, 5V and 12V DC that the computer uses. A secondary purpose is to provide air flow in the case. The heat output of computer components is increasing. To cope with this case fans have become the primary exhaust in most systems. This has lessened the importance of the PSU as a provider of airflow in the case. What are the ATX 1.3 and the ATX 2.01/2.2 PSU standards? The ATX PSU standard is a standard set by Intel. The ATX 1.3 standard was released in April 2003. This standard was the first PSU standard to include SATA connectors. At the moment this is the most common standard for PSUs. ATX 2.01 was released in June 2004. This was a major update of the ATX PSU standard, making the PSUs more suited to the modern PC with its increasing load on the 12V line of the PSU. Graphics cards and the CPU(s) are the main consumers on the 12V line. The latest version of this standard, ATX 2.2, was released in March 2005. What are the main differences between the ATX 1.3 and ATX 2.01/2.2 standard? The ATX connector  The ATX connector has changed from having 20 connectors to 24 connectors. The added connectors are 12V1, 5V, 3.3V and COM. Second 12V line added The purpose of the addition of a second 12V line on the power supply was to eliminate power surges on the 12V line when the CPU suddenly changes from idle to full load. SATA connectors  The SATA connectors have changed from being optional in the 1.3 standard to being compulsory. The standard does not state how many SATA connectors the PSU should have. Efficiency Efficiency has been changed from just being recommendations to being a requirement. The required minimum efficiency is 70% for full load and typical load, and 60% for low load. There is still recommended efficiencies in ATX 2.01/2.2, these are 78% for full load, 80% for typical load and 75% for low loads. Full load is 100%, typical load is stated as 50% of overall output and low load as 20% of overall output. Fan types and fan positioning Will the PSU fan positioning work well with the case it will be in? Check if your case is designed with a PSU fan position in mind. Most cases are design to work with any type of PSU. But some cases work best with a PSU with front or back mounted 80mm fans and some are designed for a 120mm PSU fan mounted at the bottom of the PSU. If you are considering a fan-less PSU, make sure that the case will have enough airflow without airflow through the PSU and that it will cope with the extra heat generated by the PSU. This might be a problem with some HTPC cases. Noise The noise level of the PSU depends on a combination of three factors: PSU fan (or lack of fan), efficiency of the PSU and case airflow. The better efficiency of the PSU, the less heat it will generate. The less heat, the less airflow will be needed to get rid of it. The less airflow, the less noise from the fan. The cooler the air is going into the PSU, the less airflow is needed to get rid of the heat from the PSU. If the PSU is the primary exhaust of hot air, then the PSU fan will have to work much harder to handle both the heat from the other components and the heat from the PSU. Length and type of connectors Make sure the PSU will have all the connections your system needs. Make sure that these connections are long enough for your system. This can be more of an issue if you use a case where the PSU is mounted in a separate compartment as in the Antec P180 and the Lian Li V-series. Total power output It might not be a case of the more power the better. Make sure that the PSU has enough power for your current system and future upgrades. If you use a PSU with too much power, it will be in the less efficient low output (20% of max) band of the PSU. Check the efficiencies for the PSUs you are considering and compare this to the power band of your system. |
