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just enough?


xstation

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I have been advised that the 400watt Corsair psu I am about to use on my new system is "just enough" please can I have some feedback please

 

 

cpu i7 2600

5770 ATI Readon card

2x4gigs Corsair dominator ram. 1333MHz

asus maximus IV gene-z mobo

750 gig 7200 HD

sony dvd/cd combo

zelman CNPS 10X Performa Processor cooler

 

Thanks

xstation;):

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Thanks to Wired and Gavin for your postd

 

 

The first thing is that MSI doesn't even agree with itself over power requirements. The Radeon 5770 and 6770 are the same card (just rebranded) but they list 34A 500W for the former and 25A 450W for the latter. Graphics card manufacturers run into the same problem that PSU calculators run into. They do not know the age or quality of your PSU. Thus, they have to over-compensate.

 

The Corsair CX400 is an excellent quality PSU with 30A/360W of pure +12v power. It was well reviewed, so not only do we know exactly how much +12v power it has, we know it is high enough quality to put out every single watt it claims (which not all PSUs do).

 

The Radeon 5770/6770 uses a single 6-pin PCIe power plug. These plugs are specified for 75W. The PCIe x16 slot by itself is specified for 75W. Thus we know that these cards by themselves will not use over 150W (PCIe slot + 6-pin power plug). The Core i7 CPU listed has a 95W TDP, which isn't the exact wattage it uses but is reasonably close. Both graphics card and CPU use +12v. So, now we're at around 250W worth of +12v, giving just over 100W extra for fans, HDDs, etc.

 

xstation:biggrin:

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Thanks to Wired and Gavin for your postd

 

 

The first thing is that MSI doesn't even agree with itself over power requirements. The Radeon 5770 and 6770 are the same card (just rebranded) but they list 34A 500W for the former and 25A 450W for the latter. Graphics card manufacturers run into the same problem that PSU calculators run into. They do not know the age or quality of your PSU. Thus, they have to over-compensate.

 

The Corsair CX400 is an excellent quality PSU with 30A/360W of pure +12v power. It was well reviewed, so not only do we know exactly how much +12v power it has, we know it is high enough quality to put out every single watt it claims (which not all PSUs do).

 

The Radeon 5770/6770 uses a single 6-pin PCIe power plug. These plugs are specified for 75W. The PCIe x16 slot by itself is specified for 75W. Thus we know that these cards by themselves will not use over 150W (PCIe slot + 6-pin power plug). The Core i7 CPU listed has a 95W TDP, which isn't the exact wattage it uses but is reasonably close. Both graphics card and CPU use +12v. So, now we're at around 250W worth of +12v, giving just over 100W extra for fans, HDDs, etc.

 

xstation:biggrin:

 

The MSI list is based on manufacturer recommended minimum requirements, the recommendations of prestigious sites such as TomsHardware.com, OverClockers.net, Guru3D.com,ect and end user experience. I don't use the chart myself. I employ the 20% rule to find out the minimum size power supply I should be looking for to power a system. Find out what the videocard manufacturer's minimum recommendation is for wattage and +12volt amperage then add 20% to both values. That's the minimum wattage/amperage supply one should be looking for in any system you intend to be gaming with. Never ran into a problem by following this rule and as a bonus the supplies typically outlive the warantee by a couple of years or more. Never want to starve a system for power or you'll be chasing random inexplicable problems till you're blue in the face. Been there, done that, definitely no fun.

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