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Does 650 watt psu recommendation = 650 watt 80 plus?

Go to solution Solved by Average Nerd,

The advertised wattage of a PSU is after the power losses were subtracted.

So a 650W PSU will output up to 650W, but consume more than that.

For a pc im building, im getting a rtx 3070, which recommends a 650 watt psu. Does this mean that it wants a 650 watt psu or a psu that will end up with at least 650 watts like a 800 watt 80 plus psu so that after the 20% loss it's still 650 watts?

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7 minutes ago, Fat Cat11997 said:

For a pc im building, im getting a rtx 3070, which recommends a 650 watt psu. Does this mean that it wants a 650 watt psu or a psu that will end up with at least 650 watts like a 800 watt 80 plus psu so that after the 20% loss it's still 650 watts?

650w is what it needs for you to run everything with no issues,  a 650W PSU for the RTX 3070, they are referring to the output power of the power supply unit (PSU) after efficiency losses. This means you should choose a PSU that can deliver at least 650W of power to your system components.

 

An 80 Plus certified power supply is rated for its efficiency at different load levels (20%, 50%, and 100%). For example, an 80 Plus Gold certified PSU guarantees at least 87% efficiency at 20% load, 90% efficiency at 50% load, and 87% efficiency at 100% load. This means that if you have an 800W 80 Plus Gold PSU, it would provide at least 87% of that power at full load, which is still more than enough to cover the 650W recommendation for the RTX 3070.

 

To clarify, you do not need to account for the efficiency rating when choosing a PSU; simply ensure that the advertised wattage of the PSU meets or exceeds the recommended wattage for your components. In your case, a 650W 80 Plus Gold, Silver, Bronze, or even an 80 Plus White certified PSU should be sufficient for the RTX 3070, assuming your other components do not have unusually high power requirements.

 

However, it's always a good idea to have some headroom with your PSU choice, as it can provide better efficiency, reduce noise (due to the fan not needing to work as hard), and accommodate future upgrades. In this context, choosing a reliable and well-reviewed 750W or 800W 80 Plus certified PSU may be a good investment for the long term.

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59 minutes ago, Fat Cat11997 said:

For a pc im building, im getting a rtx 3070, which recommends a 650 watt psu. Does this mean that it wants a 650 watt psu or a psu that will end up with at least 650 watts like a 800 watt 80 plus psu so that after the 20% loss it's still 650 watts?

Theres a bit more to it than that, generally 80plus certificates get better than 80% efficiency unless at extremes, and the rest of the system specs are also to be taken into account, a 7800X3D only takes around 90W of power, but a 139000K can draw 240W of power and so a higher Wattage PSU might be necessary in that scenario

 

What is your entire system specs?

System specs:

 

 

CPU: Ryzen 7 7800X3D [-30 PBO all core]

GPU: Sapphire AMD Radeon RX 7800 XT NITRO+ [1050mV, 2.8GHz core, 2.6Ghz mem]

Motherboard: MSI MAG B650 TOMAHAWK WIFI

RAM: G.Skill Trident Z5 NEO RGB 32GB 6000MHz CL32 DDR5

Storage: 2TB SN850X, 1TB SN850 w/ heatsink, 500GB P5 Plus (OS Storage)

Case: 5000D AIRFLOW

Cooler: Thermalright Frost Commander 140

PSU: Corsair RM850e

 

PCPartPicker List: https://uk.pcpartpicker.com/list/QYLBh3

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The advertised wattage of a PSU is after the power losses were subtracted.

So a 650W PSU will output up to 650W, but consume more than that.

English is not my first language, so please excuse any confusion or misunderstandings on my end.

I like to edit my posts a lot.

 

F@H-Stats

The Folding rig:

CPU: Core i7 4790K

RAM: 16 8GB (2x4GB) DDR3-1600

GPU 1: RTX 2070 Super

GPU 2: GTX 1060 3GB

PSU: Gigabyte P450B EVGA 600BR EVGA 750BR

OS: Debian 12 (it works, or at least tries to [as of now, it's majorly broken])

.- -- --- --. ..- ...         

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Hi.

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Max power draw of a 3070 is around 220w. The reason why the recommended psu is 650w is in consideration of all available combinations of parts. Plus in terms of PSU, in laysman's terms the ***watts 80plus rating means whatever wattage that specific psu is, that what it would draw at 80%. Like a 650watt with 80plus, rating can actually draw up to 800w at 100% load. But that's not recommended.

 

As for counting pc power draw in choosing a psu, the personally rule of thumb that I adapted is to make sure that the sum of all parts when computing power draw is only around 70-80% of my psu's wattage rating. So that even if there's spikes in the power draw, there won't be any issue. How does that work? For example, let's say the gpu is 3070 so that's 220w. Then I'm going to look for my cpu's maximum power draw. Let's say it's a ryzen 5800x, which around 105-110w. Then added another 50w, for other components, like ram, storage, rgb, etc. 100w is actually already high, but just to be safe. So that's 220w+110w+50w=380w.

Since the 380w, is an estimation of full load on all component(gpu and cpu), it shouldn't even be possible and actual draw should actually be lower than that. Using the rule of thumb, even a 500w 80plus rated psu would be enough to power 5800x+3070 setup at the 380w is around 75% of 500w. Then you add the optimization of undervolting. It's not just possible, it's been done already. So what that means is 650w psu is more than enough for your 3070. If you haven't yet, watch videos on how to overclock and undervolt gpu and cpu. 

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