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I have a PC I've already built, but I want to minimize it's footprint by getting a smaller case and smaller PSU. I've got a 600w SFX by corsair, but I want to move to a 300w black TFX by Silverstone.

Here are my components:

  • Crucial 1TB M.2 SSD.
  • Kingston 120GB M.2 SSD.
  • ASUS STRIX Z270i motherboard.
  • MSI GTX 1070 Aero.
  • Intel i7-6700k
  • Corsair SF600.
  • Thermaltake Engine 27
  • 2x 120mm black Noctua fans.
  • 2x Kingston HyperX DDR4 16GB RAM.

What is the minimum wattage for this system, idle and under load? What could I trim off or change to reduce power usage?

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    Why would you want to move down to a 300w PSU? Your graphics card recommends a 500w PSU. If I were you, I would keep what you have or increase the capacity rather than decrease. – DrZoo Jun 7 '17 at 20:18
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    You don't want to push your PSU too close to its max, cause if you ever go over you could start seeing inconsistencies. That being said, if you really want to see how small a PSU you can put in your system (maybe you've found a smaller form factor PSU?), your best bet is to actually measure your power consumption using something like this – ashbygeek Jun 7 '17 at 20:23
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    Try Cooler Master's Power Supply Calculator, it is super helpful. – Julysfire Jun 7 '17 at 20:32
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    It's all a compromise - a high performance system will use more power. If you ditch the GPU and use the onboard one that will reduce your max power draw by close to 150 watts, and you MIGHT get away with 300 watts without it. Your CPU draws 91 watts. A low power variant will reduce performance but could save you 50 watts. This would mean you could also replace the fan with something lower power and quieter - your fan is rated at 70 watts! – davidgo Jun 7 '17 at 20:43
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    @sawdust: oh, i agree, the reason I didn't make an answer is that it is tangental. But I was presuming it would be below maximums as the OP was speaking about reducing hardware and making calculations. The main point (again) is that the load is what matters and the inefficiency at that load is the only real savings between a large PSU and a small one. But we have since learned that this is soley about getting a smaller physical PSU – Yorik Jun 8 '17 at 14:25
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The way to determine you system wattage is to find the wattage of each component and add them up.

Using the basic information provided in your post and the Cooler Master calculator linked in the comments, your system draws over 300 watts in its basic form.

A 300 watt power supply will be insufficient and should not be used. 400 watts is the absolute minimum, given the current configuration, and realistically, for system stability and component longevity, 500 or 600 watts should be a target PS size.

  • Any recommendations for component changes? – FatalSleep Jun 7 '17 at 21:04
  • E.g. if I had 1 M.2, no extra fans and an i7-700? – FatalSleep Jun 7 '17 at 21:05
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    Recommendations are not something we can do well here, but I'd suggest dropping the smaller SSD, going from the 1070 to the 1050 GPU, which runs entirely on board power and has a TDP around 45W IIRC, and dropping one of your memory sticks entirely (more than 8GB is overkill unless you're building a power system, and if you're building a power system you're not limited to a 300W PSU). – music2myear Jun 7 '17 at 22:21

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