K
kony
Not CPU. Motherboard may, memory might, but those too can
use 5V, depends on particular manufacturer's design.
Not CPU. Motherboard may, memory might, but those too can
use 5V, depends on particular manufacturer's design.
C
Chip
Watson A.Name - "Watt Sun said:
Ever seen an electronic flash on a camera?
Hint: the flash is *very* short in duration.
Chip
C
Chip
D
David Maynard
Chip said:
Ah. So they put both on the label. ok.
C
Chip
David Maynard said:
"OK"? Well sort of. The idea that you have a "550W" PSU with a maximum 12V
supply of 14A I would say is "sharp practise" at best, and fraud at worst.
Chip
C
CBFalconer
Chip said:
Not necessarily. However it does mean that the 5V and 3.3V lines
must supply approximately 75A together.
M
Mike Tomlinson
larrymoencurly said:
That is nasty, isn't it? Take a look inside a Fortron Source (Sparkle)
power supply and compare it with that pic.
agreed. and that's without the LED fans...
D
David Maynard
Chip said:
I didn't mean it was an 'OK' practice. I was acknowledging the correction
to my (mis)understanding that the real amps were less than what was on the
sticker.
C
Chip
David Maynard said:
Oh I see. Sorry for the misunderstanding!
Chip
C
Chip
Michael Brown said:Err, I think he was making a jokeThe above circuit would indeed supply
600W of power at something around 5V for a very brief period of time if
the
capacitor was up to it. Assuming we're talking ATX tolerances (5% on 5V
IIRC), the supply voltage would be allowed to drop to 4.75V before it
became
out of spec. If the "power supply" was allowed to be on for a while before
any load was applied (ie: it charges up the capacitor) then a 1000uF
capacitor should be able to hold it within spec at a 600W load for about
2uS. The resistor and power source don't have a big impact while the load
is
applied precicely for the reason you noted: the resistor limits to
satisfying a ~6mW load at best.
I think its a 10% spec on the 5V line, so you'd be OK for around 5 uS ;-)
LOL
D
David Maynard
Chip said:
No problem.
I had only seen a 'review' by a less than satisfied customer and it gave me
the impression the 'real' power wasn't on the sticker.
Ah. I went back and found the message. The site with the review was:
http://www.casetech.co.uk/product_info.php/manufacturers_id/50/products_id/231
But I can't get it to connect right now (server times out).
The PSU the original poster (with startup problems) had was a Q-Tec 400W
Dual Fan Gold.
http://www.qtec.info/products/product.htm?artnr=13023&specs=1
The 'reviewer' claimed to have asked for, and received, specifications from
Q-Tec and described it like:
Total "Real" power output [W] 300 (not 400)
Output current +5V [A] 25A (Sticker 30A)
Output current +12V [A] 12A (Sticker 16A)
Output current -5V [A] 0,5A (Sticker 1,0A)
Output current -12V [A] 0,5A (Sticker 1,0A)
Output current +3.3V [A] 14A (Sticker 20A)
Output current +5V STB [A] 1,5A (Sticker 2,0A)
Maximal total power for 3.3 and 5 combined [Watt] 150 W (Sticker 180W)
That gave me the impression only the 'sticker' number was on the sticker.
Or maybe that's the case for the 400 watt dual fan gold and the other one
has both listed.
K
kony
The sad thing is that even based on the sticker it's
pathetic for a 400W PSU. Well, I guess you can't have it
BOTH ways, better to have a small lie on the sticker than a
larger one.
W
Watson A.Name - \Watt Sun, the Dark Remover\
[snip]
The -5V and -12V regulators on most of the PS boards I've seen are 7905
and 7912 regulator chips, and they usually have no heatsink and are just
sticking up from the PCB supported by their three legs. So they have
littls dissipation capability. So the designers rate them for a half
amp, altho they are capable of handling a full amp with a decent
heatsink. So this is a 'design compromise' I guess you'd say. But on
occasion I have seen them with a small heatsink attached.
If you look inside of a PS for a server, and then look inside a consumer
grade PS, you will immediately get the picture of where they make
'design compromises' in the consumer PS. The server PS will have big
heavy extruded aluminum heatsinks, and the consumer PS will have a sheet
of tinned steel instead. And the server will not skimp on the cooling
fans like the consumer PSes do.
The -5V and -12V regulators on most of the PS boards I've seen are 7905
and 7912 regulator chips, and they usually have no heatsink and are just
sticking up from the PCB supported by their three legs. So they have
littls dissipation capability. So the designers rate them for a half
amp, altho they are capable of handling a full amp with a decent
heatsink. So this is a 'design compromise' I guess you'd say. But on
occasion I have seen them with a small heatsink attached.
If you look inside of a PS for a server, and then look inside a consumer
grade PS, you will immediately get the picture of where they make
'design compromises' in the consumer PS. The server PS will have big
heavy extruded aluminum heatsinks, and the consumer PS will have a sheet
of tinned steel instead. And the server will not skimp on the cooling
fans like the consumer PSes do.
D
David Maynard
Watson said:
Design 'compromises' are always made. I simply expect the sticker to
reflect the design.
F
Franklin
The 35A on the +5V line might save them?
C
Chip
Franklin said:
Save them from what? From being a laughing stock? Not in my book.
Chip
K
kony
Huh?
"Output current +5V [A] 25A (Sticker 30A)"
Compare to name-brand 400W units that can sustain 40A 5V.