the powersupply myth?

[glugglug]

I wonder.... does your machine benchmark the same as a similar config with a real PSU?
Its possible they have speedstep rigged to kick in if the PSU gets overloaded (which HAS TO happen when they have 50W P4 systems).

 

[miken]

A lot of the problem is that if you have a low quality PS, you run the risk of the PS not being able to handle all the 5V and 12v lines being used at once. All PS should be able to run a MB, HD,CD and accessories, but when you start building on that with extra components is where alot of the lower quality ones fail. They compensate for that by giveng you a higher wattage, which will theoretically fix that problem, however the rails may still not be quite up to standards, plus when you run higher wattage you tend to stress components in the PS more, causing problems over time.

If the rails can output 12v and 5v consistantly under load with all connectors used I don't care what the wattage is.

 

[psteng19]

Originally posted by: Lord Evermore
OEMs get PSUs that are specially built, so even though it might be made by a company you've never heard of, they've built it to the specs of the OEM, who tests to make sure that it can power the exact system configurations they're using it in. A retail power supply is expected to be used in widely varying setups, so they can't make it a low wattage with tweaked outputs like Dell or HP gets.

There is however still a myth about high wattage being needed. The total wattage isn't really that important, it's how much power is output on the rails that are needed. Most PSUs have HUGE amperage coming out of the 5.5 and 3.3V lines, even though those are barely used even in a half-way loaded system. Then they have hardly enough power on the 12V line. Cheap 400W PSUs often have a 12V rating similar to a brand name 300W, and that's where the main difference is. It seems to be easy for a PSU maker to ratchet up the 5.5 and 3.3 rails, so they can make a high wattage PSU without putting the cost into making a good 12V rail (I assume that it costs more to do it right).

I always thought it was 3.3V, 5V, and 12V

Anyway, back to the topic... I think it's all a myth too.
I've run many AMD power hungry systems (t-bird 1.4, xp1800+) on 250W no-name branded PSU's without running into much problems.
Of course it's true that the quality PSU's are better than the generic ones, but are they really necessary for ALL users/systems?
I guess that's what marketting has done to us as consumers, fooling us to believe that we need 400+ watt PSU's.

Hey, if the Shuttle XPC's can run XP2600+'s and 9700 Pro's on a 200 watt PSU fine...

 

[bozo1]

I think part of the confusion came from AMD. Starting with their XP line, they stated that you need a powersupply that can provide a minimum of 30A on the 5-volt line and 180W on the 3.3V and 5V lines combined.

The only powersupplies that claim to do that are 'some' name-brand 300W ones. For other supplies, you need to be in the 350+W range before those specs are met.

Whether that amount of power is truly needed is up for debate, but I guess AMD thinks it is.

 

[Jhhnn]

The real issue is quality. That factor is easy to judge in person- pick 'em up, check the weight. Better psu's have heftier transformers, chokes, heatsinks, capacitors, everything. So they run at a lower % of their actual max output, and have higher peak output. That's what allows some micro supplies to work as well as they do- they have strong peak output, only required at boot, and enough beef to absorb the momentary heat peak, dissipating it quickly once the system draw settles back to its much lower running state.

The voltage may momentarily sag at boot, not a big deal except with heavily overclocked systems. These are a special case, they need that rock steady voltage instantaneously, otherwise boot failure occurs.

Boot is generally the time any weakness in the psu will show up- as boot failure, or as psu failure. The infamous Deer "POP!" accompanied by a puff of smoke is the worst case scenario.

Modern AMD and Intel systems have somewhat different requirements- AMD boards generally derive processor power from the 5v, while Intel boards use the 12v. Some of the Tweakers' type AMD boards don't use the 3.3v at all, giving regulation problems with some otherwise good supplies, notably Enermax.

There's a fair amount of exaggeration with cheapo psu's, some might refer to it as lying, cheating, stealing or fraud. The notion that you'll get a quality unit when the case is $35 and the same box w/ 450w psu is only $15 more is, uhh, not an educated pov, imho. Everything will be fine, though, for a year or so, and then, one day, you'll try to boot up....

 

[ZippyDan]

the name on the HP powersupplies is HIPRO. any one familiar with them?

~Zippy!

 

[ZippyDan]

answering my own questions i suppose

http://www.anandtech.com/showdoc.html?i=1128&p=17

old Anandtech article from Athlon Thunderbird 700 era, compares Antec, Hipro, Sparkle, Delta, and more. the Hipro does pretty well. no failures 250watt model though... running an old TBird. still encouraging

~Zippy!