a) that table is 100% CYA, representing numbers designed around making it
extremely unlikely that someone should blame Nvidia for telling them to buy a too-weak PSU for their GPU. It also factors in people buying utter crap PSUs because they don't know any better. I take for granted that people
do know better, as I tell them as much. You should
never skimp on your PSU. Period.
b) Who uses PCIe network adapters? In my experience people either buy motherboards with it built in, or use USB adapters. Regardless if it's m.2, PCIe or USB, it doesn't use more than a few watts (it's all the same base hardware anyway).
c) My formula
explicitly accounts for storage devices (and fans, pumps, motherboards, RAM, etc.). If you see it as likely you'll add more in the future, feel free to add another 5-20W to your numbers, though the 20% margin makes that safe for most people. After all, most SSDs consume <5W, and most HDDs consume <20W for a couple of seconds during spin-up and ~5-10W in use. That's not a massive addition by any means.
Adding a PCIe WiFi 6 card and an external backup HDD to your PC does essentially nothing to its overall power draw. External bus powered HDDs pull less than 5W (they're mostly 5400rpm 2.5" drives - 3.5" drives need external 12V power after all, and the bus powered ones need to work on 5W-limited USB ports), PCIe network cards are a few watts - let's be generous and say 10. If 15W is the difference between your PSU being stable and not, you're not even close to following my recommendations. Unless, I guess, your calculations told you that you needed a 90W PSU, as that's how low you'd need to go for the 20% margin to be exceeded by that additional load.
An example: A user has an i5-9400, a stock power GTX 1060, 2x8GB of DDR4-3200 and a 1TB SATA SSD. Two case fans + a 240mm AIO. With my formula that's 100W (
134W load minus 44W idle, + 10W for CPU idle power) +
125W + ~25W for the motherboard and RAM + 5W for the SSD, 20W for four fans and another 5W for the AIO pump = 280W. Add the 20% margin and you're at 310W. That's not a lot at all, and there are no quality PSU options that low, so their closest option is a 450W unit, with a 550W likely costing the same and having better availability (and likely a higher efficiency rating). That's of course complete and utter overkill, and leaves them
tons of headroom - the PC will literally never exceed 50% PSU load! - but that's reality. They can add whatever upgrades they want. But if they want to go SFF with a custom PSU or external power brick, they can also feel safe that that will be entirely sufficient, despite the scaremongering from Nvidia that the 1060
needs a 400W PSU. If, on the other hand, there were high quality 300W PSUs out there, I would say that those are
sufficient, while cautioning that it's too tight to allow for any upgrades in the future that add noticeable power draw. 350W would be entirely fine. Again, as long as the PSU is of decent quality - but that's a base necessity no matter what.
On the other end, if someone has a higher end build - let's say an i7-9700K, AIB RTX 2060S, 2x8GB of DDR4-3600 and a 1TB SAT SSD, with the same cooling. That's (
180W-41W+10W=) 150W + 205W + 30W mobo/RAM + the same 25W for cooling and 5W for an SSD. That adds up to 415W, or 498W with a 20% margin. If they plan to OC, just replace 180W for the CPU with 237W and go from there. They could in other words still get by just fine with a 500-550W PSU at stock, and the 20% margin would let them upgrade to, say, a stock-clocked RTX 2080 (226W according to TPU) without even getting close to the rating of the PSU (still just 436W), or an aftermarket one (likely more like 460W) with still little risk. Why?
Because that PC will never consume 415W under load. That number is made by adding up the
peak power numbers of every single component, a scenario that will
never happen in the real world unless you work very hard to make it happen. Games don't stress your CPU to 100% power draw, nor your drives, peripherals, or anything else. In the
vast majority of scenarios, games stress your GPU 100%, 1-2 CPU cores 80-100%, and the rest of the system is relatively relaxed, with bursty drive loads and continuous, irrelevantly small loads from RAM and peripherals.
I'm not saying this formula is idiot-proof - nothing is! - but it does the job as long as you know what you're planning and those plans don't include massive upgrades. Which most people don't plan for, or have the funds for.
