930~960w on 1000w psu. safe or not?

[ben8jam]

If you were running a 1000W PSU at full capacity, meaning your components are pulling 1000W from the PSU, your Kill-a-watt would register somewhere close to 1175W (assuming your efficiency dropped to around 85% at full power). That's a lot of wasted energy due to heat.

So even if your kill-a-watt is sayin 950W, your PSU is probably only delivering 810ish watts.

The 80% rule is a very broad term that came from server PUDs and also applies to household fuses which will flip due to excess heat generated by running continously at over 80% of the circuits max load (usaully 15a or 20a for households).

[ben8jam]

I have 850W  PSU running on full capacity for about 3 month non-stop and it works fine

If your kill-a-watt is registering 850W, then you PSU is only supplying 680 Watts if we assume 85% efficient at max power. If you bought a larger PSU, say 1000W and ran the same rig (680W draw) it would register 740W on the Kill-a-watt. So you are throwing away 100W per hour. Which is about $130 a year at .15c/kwh. Which is the cost of a 1000w psu about

If your PSU is less efficient than 85% at max, then you are wasting even more money.

[uDwcHYO]

it is better to leave a reserve of about 20%, it's not server power units that are designed for continuous work

[Za1n]

I use the same ration as the NEC does for normal electrical circuits, meaning 80 for continuous use. So for a 1000 Watt PSU, that would mean 800 watts are available for use in the system.

Now if you go over this by a small margin, say 820 to 840 watts you will probably be ok, but when you are starting to run at 95% load 24/7 things can get hot. While the first week or two you probably won't notice anything, overtime the components start to wear faster and wires get hot and you can have a fire hazard on your hands.

All around I think the 80% ration is the best rule of thumb to go by as saving a few dollars on a undersized PSU isn't worth the risk to you or your home.