"N_B_DK" <N_B_DKSPAM@SPAMhotmail.com> skrev i en meddelelse
news:ccksvi.3l4.1@communicator.dyndns.dk...
> Egil Solberg wrote:
> > Dersom Q-Tec siger de har på markedet et 400W PSU betyder det ikke at
> > man i realiteten kan trække 400W fra det. Snarere mellem 250 og 300W.
>
> Det siger da kun at det *ikke* er en 400W PSU....
>
> > Et Fortron PSU på 300W kan tit yde betydelig mere end 300W.
>
> Fint nok, så performer de jo blot bedre end de opgiver i deres datablad
over
> de(n) model(ler).
>
> > Var det så svært at forstå, da det jo har været oppe at vende en del
> > gange og jeg presenterer sådan set ikke noget nyt.
>
> Ja for det er noget ævl....
Nej Egil har fat i noget af det rigtige.
En billig 400W PSU vil ofte yde noget dårligere end en dyr kvalitets 400W
PSU.
Her taler jeg igen om den opgivne værdi.
I realiteten kan den billige måske i praksis kun levere 300W, mens den dyre
sagtens kan levere 400W.
Der er også forskel på hvordan de 400W leveres, en del billige PSU'er deler
kredsløb for 3.3V og 5V, dette gør at når belastningen stiger på eks. 3.3V
kan man ikke belaste 5V så meget.
En Q-Tec kan for eksempel ikke 100% levere det den lover.
Onkel Tom (som jeg ellers hader) havde et uheld hvor en PSU eksploderede
under en belastning, der var et godt stykke under det den var opgivet til.
Se evt. dette (lidt lange) citat:""Traditional power supply designs
typically feature circuit sharing for the 3.3V and 5V lines off the output
transformer. That means that as you increase the load on one output circuit,
the available capacity for the other decreases - for example as you load up
on devices that use 5 volts (like drives and PCI cards), you have less and
less ability to power devices that need 3.3 volt output (like your CPU). In
addition, by connecting the two systems at this point you increase the
chance of having interactions between the output circuits - for example, a
sudden 5V draw could potentially cause the voltage on the 3.3V line to drop,
harming system stability."
That's Antec's way of saying that a cheap power supply may borrow from Peter
to pay Paul. Shared circuits for the 3.3V and 5V lines mean that as you
increase the load on one output circuit, the available capacity for the
other decreases. Devices that use 5 volts (like drives and PCI cards) may
take power away from devices that need 3.3 volt output (like your CPU).
This, of course, could turn into A Very Bad Thing and lead to system
instability.
Antec's dedicated output circuitry for each voltage line should mean
consistent power regardless of load. To test that capability we used a
digital multimeter (see here for an excellent excellent pictorial on how to
do this). Please note that one should always exercise caution when working
with electrical equipment, particularly power supplies. Unless your goal in
life is to win a Darwin Award. To test the PSU without an electrical load we
attached a wire to the green power line and a black ground line on the main
power connector (this allows the PSU to start without being connected to the
PC). The 3.3V line was tested Motherboard Monitor v5.5.2.0 and the 5.5V line
was tested by using the red wire from a spare 4pin Molex connector (the kind
that goes into drives)."
Kilde:
http://www.bjorn3d.com/read.php?cID=242
Læs også her:
http://www.short-media.com/review.php?r=133
Her er også et billede af indmaden i to PSU'er.
http://www.short-media.com/forum/showpost.php?p=128872&postcount=13
Den øverste er en Channel Well Tech., den nederste er indmaden i en billig
PSU.
NB: Det er Channel Well der laver indmaden til de fleste Antec PSU'er.
Vægt er faktisk en god indikation af kvaliteten på en PSU, jo tungere jo
bedre.
Fordi jo tungere den er, jo kraftigere komponenter er der brugt, bl.a. kan
der være forskel på køling osv.