sasikanth8
Explorer
There are many factors that must be considered when selecting a PSU, or Power Supply Unit, when building a new PC or replacing a bad PSU. If you are reading this you probably understand that you want a safe PSU, one that won't fail and damage your components in the process.
Things to Know about PSU
System heat and the effects on the PSU
Most PSU’s are tested at 25 degrees Celsius, which is unrealistic. There is no PSU running in any computer environment that will be “living†in a 25 degrees Celsius environment. The realistic inside temperature of most computers is higher than room temperature and when fully loaded can sometimes get as high as 50C". That temperature increases under high stress computing like gaming.
Efficiency rating of the PSU
A higher stated efficiency rating is normally good but not always an indication of a higher quality or better built PSU.
Certification-20 Percent 50 Percent 100 Percent
80 Plus -80 Percent 80 Percent 80 Percent
80 Plus Bronze- 82 Percent 85 Percent 82 Percent
80 Plus Silver -85 Percent 88 Percent 85 Percent
80 Plus Gold- 87 Percent 90 Percent 87 Percent
The role of Power Factor Correction ( PFC)
A switching power supply converts power from your AC line into the DC voltages needed to run your computer. A standard switching power supply doesn't draw its power from the AC line smoothly. It actually draws sudden gulps of current. That "messes up" your AC power lines. In some offices with lots of equipment with switching power supplies, you can actually overheat wiring and trip current breakers because of the way they gulp power. Power factor correction smooths out the gulps to keep your AC line all nice and clean.
There are two kinds of power factor correction: active PFC and passive PFC. Active PFC is more expensive and does a better job of keeping your AC line clean. Passive PFC is cheaper but is still an improvement over not having PFC protection.
Protection Features
Manufacturers that offer numerous Protection options on their PSU’s normally indicate a higher quality product, while a lower quality unit will not offer as many of these features.
OVP = Over Voltage Protection
OCP = Over Current Protection
OPP = Over Power Protection
SCP = Short Circuit Protection
UVP = Under Voltage Protection
OTP = Over Temperature Protection
The motherboard main power cables
The ATX standard has two different versions of the main power cable: the original 20 pin cable, and the the newer 24 pin cable. The 24 pin cable is just the 20 pin cable with 4 extra wires added to the end to provide extra current. If your power supply main power cable and motherboard main power connector both have the same number of pins then they'll (of course) fit together just fine. But what happens if they don't match? If you plug a 24 pin power cable into a 20 pin motherboard then it will work fine but you often can't get them to physically fit together because something gets in the way. If they don't fit together then you can get an adapter cable which converts a 24 pin power cable into a 20 pin cable. You can always plug a 20 pin power cable into a 24 pin motherboard but whether it works over the long haul depends on how much current your motherboard draws. Those extra 4 pins provide more current carrying capacity. Plugging a 20 pin cable into a 24 pin motherboard can strain the 20 pins that you're using. If the motherboard draws too much current then it will overheat the connector which can burn or melt it. There are adapters which convert 20 pin cables into 24 pin cables but they don't solve the problem and can cause problems of their own. Many newer power supplies come with a 20+4 power cable which has a 24 pin connector which can be split into two pieces: a 20 pin piece, and a 4 pin piece. This kind of power cable is fully compatible with both 20 and 24 pin motherboards. If you're buying a new power supply then try to get one with a 20+4 power cable.
There are many other factors like
Capacitor quality (is important in a power supply),
single rail/multiple 12 volt rail(prefer single rail) etc...
We can stop here because there are many other things which are complex to understand.
Determining wattage requirements for your selected machine
Atomic MPC forum
http://http://forums.atomicmpc.com.au/index.php?showtopic=264
As the GPU is the largest single load on your PSU, this table can take you a long ways in determining your needs.
Extreme Outervision power estimatorhttp://extreme.outervision.com/psucalculatorlite.jsp
This is the most used and best of these tools, but it uses wattage not 12V amps.
Add another 50watts as a safety measure.
Quickly determine your wattage requirement here
22-34 amps - Often "400W" PSUs
This is the range of power you need for the modern basic office machine or simple HTPC. Any PC with lower powered graphics, only a few fans and hard drives, etc.
*rankedpsulist [...] 4amps.html
35-42 amps - Often "550W" PSUs
This is the range that many gaming computers will use. Can support most single video cards but not all. Can support 2 lower power video cards although usually the next range is better for those.
*rankedpsulist [...] 2amps.html
43-54 amps - Often "650W" PSUs
This range is a good choice for the gamer with two moderate video cards or one very high power card. Start adding in a lot of hard drives, fans, water-cooling... and you might be more comfortable in the next range, especially with moderate overclocks of the CPU and GPU(s).
*rankedpsulist [...] 4amps.html
55-64 amps - Often "750W" PSUs
This range will be fine for most systems with two larger video cards and the usual assortment of gaming parts. It might also be a good range for those just wanting room to grow into whatever. It cannot handle everything however - there are limits.
*rankedpsulist [...] 4amps.html
65-75 amps - Often "850W" PSUs
This range is enough for just about anything. Two large overclocked video cards, a well overclocked CPU, a large RAID, fans & lighting, this range can handle it.
*rankedpsulist [...] ~850w.html
76 or more amps - Often "1000W" or "1200W" PSUs
This range is large and covers the rest. If you have 3 large video cards you may need this much. FOUR large GPUs, TWO water-cooling loops, 8 fans, 8 hard drives? Or maybe you just want to keep that option open? Then you need something like this.
*rankedpsulist [...] igher.html
Some links are provided above which had different ranks.
Here's what those ranks mean.
*Rank 1 never has more than 5 units in a given power range, and is the best. Almost all units in this rank should be fully modular.
*Rank 2 has PSUs that are almost as good as those in rank 1. Maybe they were bumped out of rank one, or maybe they were placed there because of similarities to former rank 1 units.
*Rank 3 has PSUs that are good, passing all tests, but not remarkable, or with minor flaws.
*Rank 4 has PSUs that don't really meet standards and have minor flaws. Often they can be OK as long as you don't load them up too much. This is here for folks that may not have access to better PSUs.
*Rank 5 is to be avoided at all costs.
Do you think that all power supplies are manufactured by the brand on the label?
No.
Some imports PSUs from OEM manufacturers (like Seasonic,FSP) and designs fom designers (like Corsair,Tagan) those are resold under their own labels.
If you want to know who manufactured your psu and if it is fake/original check this
http://www.techenclave.com/pc-peripherals/who-is-the-manufacturer-your-psu-190415.html
We can dedicate this thread for PSU discussion.
Hope this helps to many:cool2:.
If TE likes this make it as sticky.
Things to Know about PSU
System heat and the effects on the PSU
Most PSU’s are tested at 25 degrees Celsius, which is unrealistic. There is no PSU running in any computer environment that will be “living†in a 25 degrees Celsius environment. The realistic inside temperature of most computers is higher than room temperature and when fully loaded can sometimes get as high as 50C". That temperature increases under high stress computing like gaming.
Efficiency rating of the PSU
A higher stated efficiency rating is normally good but not always an indication of a higher quality or better built PSU.
Certification-20 Percent 50 Percent 100 Percent
80 Plus -80 Percent 80 Percent 80 Percent
80 Plus Bronze- 82 Percent 85 Percent 82 Percent
80 Plus Silver -85 Percent 88 Percent 85 Percent
80 Plus Gold- 87 Percent 90 Percent 87 Percent
The role of Power Factor Correction ( PFC)
A switching power supply converts power from your AC line into the DC voltages needed to run your computer. A standard switching power supply doesn't draw its power from the AC line smoothly. It actually draws sudden gulps of current. That "messes up" your AC power lines. In some offices with lots of equipment with switching power supplies, you can actually overheat wiring and trip current breakers because of the way they gulp power. Power factor correction smooths out the gulps to keep your AC line all nice and clean.
There are two kinds of power factor correction: active PFC and passive PFC. Active PFC is more expensive and does a better job of keeping your AC line clean. Passive PFC is cheaper but is still an improvement over not having PFC protection.
Protection Features
Manufacturers that offer numerous Protection options on their PSU’s normally indicate a higher quality product, while a lower quality unit will not offer as many of these features.
OVP = Over Voltage Protection
OCP = Over Current Protection
OPP = Over Power Protection
SCP = Short Circuit Protection
UVP = Under Voltage Protection
OTP = Over Temperature Protection
The motherboard main power cables
The ATX standard has two different versions of the main power cable: the original 20 pin cable, and the the newer 24 pin cable. The 24 pin cable is just the 20 pin cable with 4 extra wires added to the end to provide extra current. If your power supply main power cable and motherboard main power connector both have the same number of pins then they'll (of course) fit together just fine. But what happens if they don't match? If you plug a 24 pin power cable into a 20 pin motherboard then it will work fine but you often can't get them to physically fit together because something gets in the way. If they don't fit together then you can get an adapter cable which converts a 24 pin power cable into a 20 pin cable. You can always plug a 20 pin power cable into a 24 pin motherboard but whether it works over the long haul depends on how much current your motherboard draws. Those extra 4 pins provide more current carrying capacity. Plugging a 20 pin cable into a 24 pin motherboard can strain the 20 pins that you're using. If the motherboard draws too much current then it will overheat the connector which can burn or melt it. There are adapters which convert 20 pin cables into 24 pin cables but they don't solve the problem and can cause problems of their own. Many newer power supplies come with a 20+4 power cable which has a 24 pin connector which can be split into two pieces: a 20 pin piece, and a 4 pin piece. This kind of power cable is fully compatible with both 20 and 24 pin motherboards. If you're buying a new power supply then try to get one with a 20+4 power cable.
There are many other factors like
Capacitor quality (is important in a power supply),
single rail/multiple 12 volt rail(prefer single rail) etc...
We can stop here because there are many other things which are complex to understand.
Determining wattage requirements for your selected machine
Atomic MPC forum
http://http://forums.atomicmpc.com.au/index.php?showtopic=264
As the GPU is the largest single load on your PSU, this table can take you a long ways in determining your needs.
Extreme Outervision power estimatorhttp://extreme.outervision.com/psucalculatorlite.jsp
This is the most used and best of these tools, but it uses wattage not 12V amps.
Add another 50watts as a safety measure.
Quickly determine your wattage requirement here
22-34 amps - Often "400W" PSUs
This is the range of power you need for the modern basic office machine or simple HTPC. Any PC with lower powered graphics, only a few fans and hard drives, etc.
*rankedpsulist [...] 4amps.html
35-42 amps - Often "550W" PSUs
This is the range that many gaming computers will use. Can support most single video cards but not all. Can support 2 lower power video cards although usually the next range is better for those.
*rankedpsulist [...] 2amps.html
43-54 amps - Often "650W" PSUs
This range is a good choice for the gamer with two moderate video cards or one very high power card. Start adding in a lot of hard drives, fans, water-cooling... and you might be more comfortable in the next range, especially with moderate overclocks of the CPU and GPU(s).
*rankedpsulist [...] 4amps.html
55-64 amps - Often "750W" PSUs
This range will be fine for most systems with two larger video cards and the usual assortment of gaming parts. It might also be a good range for those just wanting room to grow into whatever. It cannot handle everything however - there are limits.
*rankedpsulist [...] 4amps.html
65-75 amps - Often "850W" PSUs
This range is enough for just about anything. Two large overclocked video cards, a well overclocked CPU, a large RAID, fans & lighting, this range can handle it.
*rankedpsulist [...] ~850w.html
76 or more amps - Often "1000W" or "1200W" PSUs
This range is large and covers the rest. If you have 3 large video cards you may need this much. FOUR large GPUs, TWO water-cooling loops, 8 fans, 8 hard drives? Or maybe you just want to keep that option open? Then you need something like this.
*rankedpsulist [...] igher.html
Some links are provided above which had different ranks.
Here's what those ranks mean.
*Rank 1 never has more than 5 units in a given power range, and is the best. Almost all units in this rank should be fully modular.
*Rank 2 has PSUs that are almost as good as those in rank 1. Maybe they were bumped out of rank one, or maybe they were placed there because of similarities to former rank 1 units.
*Rank 3 has PSUs that are good, passing all tests, but not remarkable, or with minor flaws.
*Rank 4 has PSUs that don't really meet standards and have minor flaws. Often they can be OK as long as you don't load them up too much. This is here for folks that may not have access to better PSUs.
*Rank 5 is to be avoided at all costs.
Do you think that all power supplies are manufactured by the brand on the label?
No.
Some imports PSUs from OEM manufacturers (like Seasonic,FSP) and designs fom designers (like Corsair,Tagan) those are resold under their own labels.
If you want to know who manufactured your psu and if it is fake/original check this
http://www.techenclave.com/pc-peripherals/who-is-the-manufacturer-your-psu-190415.html
We can dedicate this thread for PSU discussion.
Hope this helps to many:cool2:.
If TE likes this make it as sticky.
Theres no problem consolidating information from different places since its useful to all of us, just do mention the source so that we don't end up with any copyright issues.