As I said, I've yet to encounter a single CPU and GPU that will fully load a good 750W unit.
Me either but... ...in reality whether or not the PSU is a "good" 750W unit or a sub-par unit really is immaterial when properly sizing a PSU for purchase. We must assume 750W is 750W even though one may be full of ripple, poorly regulated and out of tolerance. Without actual testing, we cannot assume a "good" 750W PSU can deliver more power than a sub-par 750W PSU with the same published specs on the measured rails. We can only assume the "good" PSU's output voltages will be cleaner and perhaps more stable with less wasted energy.
Of course, nobody wants instability cause by sub-par "dirty" power. I would never buy a brand new Porsche then fill it up with questionable fuel from the corner Tobacco and Bait Shop.
I think the problem is recommended vs actual needs. No table like that ASUS table, no GPU or graphics card maker, no calculator is ever going to recommend an underpowered PSU. They all pad the results. And that makes sense. And with the exception of the
eXtreme OuterVision PSU Calculator, all those tables, GPU and card makers, and (AFAIK) all other calculators use arbitrary numbers for the other components the PSUs will power. Or at least, they typically don't state how many sticks and what type RAM, how many and what size case fans, if using a conventional CPU cooler or some alternative, how many and what type drives, etc. So they pad the results even more.
When sizing up a PSU for purchase, "
IF" (and yes, now I am using a "what if") the maximum demand of the CPU and the maximum demand of the graphics solution added together total more than 750W (setting aside the demands of the mobo, RAM, drives, fans, etc.) we must assume it is possible both power hungry devices "might" max out demands at the same point in time, and make our purchase accordingly.
The problem is, we typically don't really know the true maximum power consumption of these components. And therein lies the rub. Without actual testing, we have to assume the manufacturers' published specs are fairly accurate.
So even though it is unlikely both the CPU and the graphics solution will reach peak demands at the same point in time, it is still possible. And the PSU must be able to provide it. And for that matter, we must assume at that same point in time, all fans will be spinning at full speed, all drives are being heavily accessed, all RAM are maxed out too.
If anything all this built-in padding/headroom just shows us is the advice to size your PSU to run at about "
50 to 60 percent of a PSU's capacity" really makes no sense with today's PSUs and their relatively "flat efficiency curves". All the extra headroom is already in there. There's no need to double. The only exceptions I can see would be if you are seriously planning on adding a
second graphics card in the near future or, maybe, moving from integrated graphics to a power hungry card.
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Side question - anyone aware of any stress or benchmark program that fully taxes the CPU, GPU, RAM and drives
at the same point in time? It seems to me an "artificial" scenario (like a stress or benchmark test) would be the only scenario where that might actually happen - but I am not aware of any that do that. Typical "real-world" scenarios tend to be CPU
or GPU intensive, not both at the same time - at least not for more than a few clock-cycles at once.
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