which psu to buy

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dhirajranger

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Dec 13, 2012
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hi
i am plannig to buy gtx 760 for 1080p gaming and watching 3d movies on my tv i have an old 450w psu with 16A on 12v rail i calculated power for my psu with newegg and msi power calc and it says i only need 380 watt power at peak while gtx 760 specs says to have 550+ watts of power i am realy confused should i buy a new psu and compromise with gpu?

here are my system specs

core i3 3220 (no overclocking)
kingston jetflash ddr3 1600 mhz (8 GB)
as rock h61 mobo (low power)
1 TB WD green

so do i nee a poweful psu as my system doesnt take very high power also there is no option for overclocking an i3

if i invest in a new psu i might have to wait for gpu or compromise with a cheaper one
 
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Yes that would work. Some PSUs split the 12 volt delivery into multiple rails to stay within the ATX12v maximum power on a single wire. This is optional on the latest revision of ATX12v but remains recommended. On previous versions of the ATX12v specification it was mandatory. Thus, any PSU design prior to 2007 (old, but still the latest specification) had to have multiple rails to deliver high levels of 12v power.

One of the rails will typically serve the motherboard, CPU, and MOLEX/SATA power...
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Pinhedd

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Aug 7, 2007
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You need a PSU with approximately 30 amperes on the 12 volt rail. Your system will draw less than that (approximately 25 amperes) but it's good to have some overhead.

Older PSUs, as well as cheap PSUs usually provide between 40% and 66% of their marketed capacity on the 12 volt rail. Good PSUs provide over 95% of their marketed capacity on the 12 volt rail. For example, a cheap 500 watt PSU may provide only 250 watts on the 12 volt rail, loading the rest onto the barely used 5 volt rail and 3.3 volt rail for marketing purposes. A good 500 watt PSU will provide at least 480 watts on the 12 volt rail and whatever slack is necessary on the 5 volt and 3.3 volt rails.

Component manufacturers don't want to make unsafe assumptions about the platform in which their products are being installed and set the recommended minimum based on what a typical cheap PSU would be able to safely provide. A GPU with a TDP of around 150 watts would typically recommend a 500 watt PSU as almost all 500 watt PSUs will provide at least 250 watts on the 12 volt rail. This leaves 100 watts for the rest of the platform. In that example, a good 350 watt PSU would do just as well as a cheap 500 watt PSU, and even better when efficiency is taken into account.
 
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dhirajranger

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Dec 13, 2012
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ok i get the idea of what you said
here is one more confusion there is one psu cooler master elite power which is in my budget it is 400 watts but it says 2X12v rails 18amp each thus providing 380 watts on 12 v rail would that work?
 
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Pinhedd

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Aug 7, 2007
10,342
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56,965


Yes that would work. Some PSUs split the 12 volt delivery into multiple rails to stay within the ATX12v maximum power on a single wire. This is optional on the latest revision of ATX12v but remains recommended. On previous versions of the ATX12v specification it was mandatory. Thus, any PSU design prior to 2007 (old, but still the latest specification) had to have multiple rails to deliver high levels of 12v power.

One of the rails will typically serve the motherboard, CPU, and MOLEX/SATA power connectors. Subsequent rails will be drawn out as 6 and 8 pin PCIe connectors.
 
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