Sorry Ferrari but your logic only fits a few specific examples - NOT the universal
fit we are looking for here - and therefore your position is NOT realistic for THIS situation. You are absolutely correct
about current on the +12V rail being the critical criteria (as I've noted many times here at G2G
, as a sticky at G2G's sister site, WhattheTech
, and elsewhere; when researching PSUs, the order of importance is (1) Current (amperage or amps) on the +12V rail, (2) Efficiency and (3) Total wattage. Note I too urge folks buy quality PSUs from reputable makers only. And yes, the Corsair 400 is a most excellent supply, and certainly one that will support most users better than many no-name, generics PSUs with bigger specs. But a 400W supply, with only 30A on the single
12V rail, is NOT a suitable "universal"
substitute for someone intending to use that PSU for troubleshooting purposes in a technical support business!
While your 4 card extreme case is extreme, there are many users that do run with big cards, and many with 2 power hungry cards. Some users have 5 and 6 hard drives. If you are doing PC repair for a business, you need something big enough to handle just about anything. As a formally trained technician for 35+ years, when troubleshooting electronics, after safety, I always start at the wall and make sure I have good power. When troubleshooting a power hungry computer, I regularly swap in one my "known good" PSUs. It would be irresponsible of me to use a grossly underrated PSU. A stressed PSU can overheat and become unstable, affecting everything it feeds.
So from what you are saying, that would be better than the 400 watt Corsair
I said no such thing. Do NOT put words into my mouth or twist my words around. And please understand I have nothing against Corsair, or the single rail concept - I think it superior and have a Corsair 750TX (with 60A on the single rail) running this PC.
I've already linked to a test system that clearly shows that a 5770 with an i7 overclocked to 4ghz only uses 251 watts.
The manufacturer just needs to cover it's bases because they know people try to cut back and buy cheap PSU's so they have to say 400 or 500 watts.
No. That is incorrect. The manufacturer is covering it's bases because like you and me, we do not know what CPU the user is using, what type or how much RAM will be installed, if a full size ATX or micro ATX motherboard, number of drives, fans, or what other devices will be used in those systems. Now look at these test results
from the same HardwareCanucks site using the exact same i7 overclocked hardware
- note it clearly
shows results with two cards using 419 and 420 watts. So even if you were right and the card makers were covering their bases, it is not likely the same review site, same lab, same technician even, using the same overclocked gaming test rig and testing procedures skewed these results, but not the results for your example. I don't think Dell's cheapest i7 920
would come with a 525W supply if they could get away with something cheaper.
So the bottom line is this, even the best 400W supply does not have the horsepower to fulfill the wide-ranged duties of a temporary power supply in a repair shop. Great for testing fans and drive motors, and most "office" type machines running with on-board graphics, or some entry to mid-level cards. But to temporarily replace a PSU in a big rig, something with more horsepower that can deliver the current without straining