saphalline
10-11-2008, 03:39 PM
Power supplies have gone through a lot of changes in the last few years. This is reflected by the advances in hardware that they power. PSU's will continue to change, but the flurry of activity even within the last two years demands some perspective. Just what is the latest ATX spec? What is a "new" PSU? What makes a PSU better for modern systems? While these questions are important, answering them requires delving into electrical theory, which is largely insignificant to the greater goal of picking a good PSU for your new rig. :p Let's just lay down some highlights...
PRICE - Expect a high quality PSU capable of handling today's hardware to cost you at least $60 USD. Also expect the cost to easily approach $150 USD for a gaming rig. The PSU cost should be no less than 10% of the total cost of the system, minus peripherals and OS. Upgrades are exempt.
COOLING - Any and all cooling provided by the PSU should be considered the sole property of the PSU. In other words, the PSU fans are meant to cool the PSU, not the system! When counting fans in any rig, exclude the PSU fans, as they are designed to provide adequate airflow for the PSU alone. This is an important aspect of system cooling, because hotter PSU's are less efficient, and overheating PSU's are on their death beds.
POWER DRAW - PSU's only draw as much power as they need for the system. A 1000W PSU will not consume 1000W at all times, merely when it is needed. When calculating your monthly power bill, leave the poor PSU alone! It only does what you ask of it, no more. Maximum PSU power draw occurs during system power-up; average PSU power draw is often 60% less, depending on your hardware. You buy it, you power it, but not at maximum at all times.
WATTAGE - 500W minimum for modern systems. 550W minimum if you have a dedicated vid card. 600W minimum for high-end gaming hardware. 700W or more recommended for SLI/CrossFire systems. Aim high. A 700W PSU will not draw any more power than a 500W PSU for a cheap rig, other than possibly being more efficient.
EFFICIENCY - 75% minimum. Easily accomplished by today's PSU's. 80% or more recommended for high-end gaming rigs. More than a few of these exist today. Expect to pay more up-front for increased efficiency. Expect your PSU's quality to be top-notch with 80% efficiency.
QUALITY - If you can throw your PSU at a friend without causing bleeding injuries, you should throw it out! Weight is the first indicator of PSU quality. Less than 2 lbs is a joke! The average $60 PSU is fairly hefty, and the average $100 PSU can crush a beetle! Manufacturers also play a heavy role in PSU quality, but nothing beats good old fashioned reviews. Do your research.
POWER CONNECTORS - No 24-pin main ATX power connector = fail. No SATA power connectors = fail. No PCIe power connectors = fail. For new purchases as of today, you also need: one 8-pin CPU power connector (convertible 4/8-pin or 8-pin plus 4-pin); one or more 8-pin PCIe 2.0 power connectors; four or more SATA power connectors (preferably six or more); power cable strands with no more than four of any type of power connector in series (ie, many many cable strands from the PSU).
RAIL DESIGN - Multiple +12V DC rails are common. These are fine for baseline systems through mid-range gaming rigs. 700W or more intended for high-end gaming rigs, including but not limited to SLI/CrossFire, should increasingly prefer single-rail +12V DC. Pursuant to the other qualifications, a high quality gaming-caliber 700W or more PSU should cost enough to justify the existence of quality components within the PSU to allow for high quality single-rail +12V DC design. In the case of SLI/CrossFire, a high quality single-rail +12V DC design is preferred over multiple +12V DC rails.
POWER FACTOR CORRECTION - Active PFC of 0.97 to 1.0 is preferred but not necessary. Modern high quality PSU's above $80 are likely to have 0.99 by default.
SUPPORTING DEVICES - An uninterruptible power supply (more commonly known as a "battery backup") is essential for protecting the PSU and other hardware from undue electrical stress. Surge protectors provide a mere 1/3 of the protection of a UPS, and none of its convenience. In addition to an adequate UPS, a higher quality and higher cost version with AVR (automatic voltage regulation) is preferred. These supporting devices vary in cost: surge protectors start at $10, UPS's start at $35, UPS's w/AVR start at $90. It is recommended that you spend at least an additional 3% of the total cost of the system on a supporting device for your PSU. Thus a $10 surge protector would be just fine for a $330 system.
PRICE - Expect a high quality PSU capable of handling today's hardware to cost you at least $60 USD. Also expect the cost to easily approach $150 USD for a gaming rig. The PSU cost should be no less than 10% of the total cost of the system, minus peripherals and OS. Upgrades are exempt.
COOLING - Any and all cooling provided by the PSU should be considered the sole property of the PSU. In other words, the PSU fans are meant to cool the PSU, not the system! When counting fans in any rig, exclude the PSU fans, as they are designed to provide adequate airflow for the PSU alone. This is an important aspect of system cooling, because hotter PSU's are less efficient, and overheating PSU's are on their death beds.
POWER DRAW - PSU's only draw as much power as they need for the system. A 1000W PSU will not consume 1000W at all times, merely when it is needed. When calculating your monthly power bill, leave the poor PSU alone! It only does what you ask of it, no more. Maximum PSU power draw occurs during system power-up; average PSU power draw is often 60% less, depending on your hardware. You buy it, you power it, but not at maximum at all times.
WATTAGE - 500W minimum for modern systems. 550W minimum if you have a dedicated vid card. 600W minimum for high-end gaming hardware. 700W or more recommended for SLI/CrossFire systems. Aim high. A 700W PSU will not draw any more power than a 500W PSU for a cheap rig, other than possibly being more efficient.
EFFICIENCY - 75% minimum. Easily accomplished by today's PSU's. 80% or more recommended for high-end gaming rigs. More than a few of these exist today. Expect to pay more up-front for increased efficiency. Expect your PSU's quality to be top-notch with 80% efficiency.
QUALITY - If you can throw your PSU at a friend without causing bleeding injuries, you should throw it out! Weight is the first indicator of PSU quality. Less than 2 lbs is a joke! The average $60 PSU is fairly hefty, and the average $100 PSU can crush a beetle! Manufacturers also play a heavy role in PSU quality, but nothing beats good old fashioned reviews. Do your research.
POWER CONNECTORS - No 24-pin main ATX power connector = fail. No SATA power connectors = fail. No PCIe power connectors = fail. For new purchases as of today, you also need: one 8-pin CPU power connector (convertible 4/8-pin or 8-pin plus 4-pin); one or more 8-pin PCIe 2.0 power connectors; four or more SATA power connectors (preferably six or more); power cable strands with no more than four of any type of power connector in series (ie, many many cable strands from the PSU).
RAIL DESIGN - Multiple +12V DC rails are common. These are fine for baseline systems through mid-range gaming rigs. 700W or more intended for high-end gaming rigs, including but not limited to SLI/CrossFire, should increasingly prefer single-rail +12V DC. Pursuant to the other qualifications, a high quality gaming-caliber 700W or more PSU should cost enough to justify the existence of quality components within the PSU to allow for high quality single-rail +12V DC design. In the case of SLI/CrossFire, a high quality single-rail +12V DC design is preferred over multiple +12V DC rails.
POWER FACTOR CORRECTION - Active PFC of 0.97 to 1.0 is preferred but not necessary. Modern high quality PSU's above $80 are likely to have 0.99 by default.
SUPPORTING DEVICES - An uninterruptible power supply (more commonly known as a "battery backup") is essential for protecting the PSU and other hardware from undue electrical stress. Surge protectors provide a mere 1/3 of the protection of a UPS, and none of its convenience. In addition to an adequate UPS, a higher quality and higher cost version with AVR (automatic voltage regulation) is preferred. These supporting devices vary in cost: surge protectors start at $10, UPS's start at $35, UPS's w/AVR start at $90. It is recommended that you spend at least an additional 3% of the total cost of the system on a supporting device for your PSU. Thus a $10 surge protector would be just fine for a $330 system.