Archived from groups: alt.comp.hardware.overclocking.amd (
More info?)
chris wrote:
> 500 Watts? Not for that setup!
>
> Read the following post I found:
> "I have an Athlon 64 3400+, 1024mb ram, a DVD burner, 9800 pro, a TV
> tuner and a PCI ide controller with a total of nine hard drives, 8
> ide and 1 sata. PSU is a 350W Antec Silent Blue
> It is beautiful"
Possible, but you wouldn't want to run the system under load for extended
periods of time. First of all, there is no Antec Silent Blue power supply.
I'll assume he's running a SmartBlue 350, which seems to be the closest fit.
The ratings on this PSU are:
+12V : 16A
+5V : 35A
+3.3V : 28A
with the cross-cload restrictions of 5V + 3.3V < 330W and 5V + 3.3V + 12V <
330W.
A modern 7200 RPM HDD drive consumes somewhere between 7W and 10W when idle,
almost exclusively from the 12V line. So 9 HDDs would use at least 5.5A from
the 12V line. A 3400+ typically eats 3A+ when idle, possibly more if it's a
low end motherboard (less efficient regulators). When idling, a 9800Pro uses
3.6A from the 5V line, 0.3A on the 12V line, and 2.9A on the 3.3V line. So
our idle current requirements are:
+12V: 12.1A
+5V: 3.6A
+3.3V: 2.9A
5V+3.3V : 27.6W
12V+5V+3.3V: 172.8W
Under load, a 9800 Pro consumes ~5.4A from the 5V, 0.6A from the 12V, and
4.4A from the 3.3V. A 3400+ will require at least 6A from the 12V line,
probably actually 7 or more depending again on motherboard quality and core
revision. An active HDD typically consumes 1A from the 12V line. So, if we
have the CPU and GPU under stress (eg: gaming) the current requirements go
up to:
+12V: 16.4A
+5V: 5.4A
+3.3V: 4.4A
5V+3.3V : 36.6W
12V+5V+3.3V: 238.4W
So we're already over the rated value for the 12V line. And this is without
the RAM, PCI cards, or chipset requirements taken into account. Throw in an
active HDD or two (a level load from a RAID0 array, say) and we're starting
to get significantly over the rated power for the PSU, even from an
under-predicting calculation. Sure, it might work for a while, but I for one
would not be betting on the life expectency of the PSU, or even system
stability under load.
Another real killer on that setup would be the HDD spin-up. I know that PATA
does not support sequential spin-up, and I'm pretty sure SATA doesn't
either. The spin-up for a typical 7200RPM drive is somewhere around 3A (the
older the drive the more it uses). So 9 drives spinning up would require at
least 27A from the 12V line (324W) . I'm guessing that if you stuck a
multimeter onto the power supply you'd see a huge current sag during
boot-up.
For the OP's system, a good quality 350W would probably just scrape in. I'd
feel much more comfortable with a (good quality) 400W or 450W. 500W and
above is probably overkill unless you're going to be going for a high
overclock on the card and CPU (mainly increasing the voltages will be what
gets it).
And this is coming from someone who used to talk down big PSUs ...
[...]
--
Michael Brown
www.emboss.co.nz : OOS/RSI software and more
Add michael@ to emboss.co.nz ---+--- My inbox is always open
Facebook
Twitter
Instagram