Power Supplies Question

[R3DOPS]

The question i have is how should i know what power supply should i get. If i am making a computer for a friend or myself how do i know if i should get a power supply rated at 450, 750 or more? Do i have to look up each part such as CPU, GPU, HDD, and so and and find how much watts they all take then add them up and get a total? So in conclusion.. Should i find out how many watts i need for my power supply. I just want to understand this so i don't have to worry about my power supply catching on fire because i upgraded my cpu or something. Thanks for the help! 

[thekeemo]

what parts?

[shypin]

yep you have to add them up

there are calculators online tho

[R3DOPS]

what parts?

 

Its just for the whenever i make a computer i want to know when i have to make one later.. no parts just yes and no and tips so i can understand how power supply work and so on 

[W-L]

 

Its just for the whenever i make a computer i want to know when i have to make one later.. no parts just yes and no and tips so i can understand how power supply work and so on 

 

Personally I go by TDP of the CPU and GPU with an addition 50W for most times for say LED's, fans, HDD, etc then an extra 20-25% it will give you a very rough estimate of the power consumption with some overhead built in already.

 

For example if the CPU is 95W TDP, GPU 150W TDP, the total is around 370W which the system should never reach so a 500W unit or 550W is more than enough even with overclocking.

 

 

Some other methods are using PSU calculators online which are fairly accurate:

http://outervision.com/power-supply-calculator

[WoodenMarker]

Its just for the whenever i make a computer i want to know when i have to make one later.. no parts just yes and no and tips so i can understand how power supply work and so on 

Wattage needed depends on the components you're using. 

[R3DOPS]

Wattage needed depends on the components you're using. 

Ok lets say my computer.. i have an amd 965 cpu, and a msi r7870 gpu. I have one ssd, one hdd and 3 fans. do i need to supply more info? 

[EliasNM]

If you are avoiding PSU calculators do add up the CPU and GPU these days they add up to roughly 350W minimum, then add some breathing room to how many fans and how many drives, HDDs normally are 25W, SSDs roughly use 5W IIRC, with 3HDDs and 1 SSD, a 500W PSU will do. I like leaving breathing room for upgrade so getting a 600W is even better. I didn't calculate fans into this since I am unaware of their power consumption.

[WoodenMarker]

Ok lets say my computer.. i have an amd 965 cpu, and a msi r7870 gpu. I have one ssd, one hdd and 3 fans. do i need to supply more info? 

A decent 450w would be good.