In article <(E-Mail Removed)>,
(E-Mail Removed) wrote:
> I've got a 5-year old 300w power supply (Antec PP-303X). I'm about to
> add a IDE RAID controller and another hard drive, and a few more case
> fans, and am wondering if I need a new power supply. Here's what my
> system will have after the upgrades:
>
> ABIT KT7-RAID mobo
> Athlon Tbird 1.2 GHz
> GlobalWin FOP32-1 heatsink
> 2 sticks of PC133 RAM
> 2 IDE 7200 rpm hard drives
> Matrox G400 AGP video card with 16 mb
> PCI 3ware IDE RAID true hardware controller
> PCI network card
> PCI generic soundcard
> ISA modem
> DVD-ROM drive
> CD-RW drive
> floppy drive
> USB memory card reader
> 4 case fans
> keyboard
> mouse
>
> I checked some of those online power supply calculators... the Extreme
> PSU one and the Takaman one (which were set to 80% utilization) said I
> need a PSU around 270w, and the JSCustom one said I need a PSU around
> 300w. I've read that you shouldn't exceed a PSU's wattage by 80%, and
> I also should have some "extra" wattage in case I add more components
> in the future. So do you think my 300w power supply is enough?
http://www2.beareyes.com.cn/jpic/1/2...5_212826_1.jpg
3.3@20A 5V@30A 12V@15A (-12V@0.8A -5@0.5A) +5VSB@2A
180W max on 3.3 plus 5V rails.
The KT7 RAID uses a HIP6301 according to this.
http://www.ocinside.de/index_e.html?...kt7_vcore.html
http://www.intersil.com/data/fn/fn4765.pdf (HIP6301 datasheet)
It looks like the eight pin MOSFET drivers use +12V and so the
drain for your processor is on the +12V supply (best guess)
A 1.2GHz processor is listed as 59W. At 90% conversion efficiency,
this is (59/12)*(1/0.9) = 5.46A from +12V. Which is getting pretty
close to the limit for a single pin on the ATX 20 pin power connector.
Really makes me wonder whether my sleuthing above is correct...
When idle, the three disk drives draw 0.6A each from +12V.
At spinup (the 20 seconds just after PC is switched on), the
disks can draw over 2amps a piece for the motors. So Takaman
shows the spinup power consumption, but not the normal desktop
consumption. But you are still not over the +12V limit
(5.46 + 3*2.5 = 13A of 15A available). Most supplies can
take a slight overload for the time it takes to spin up
the drives, and overcurrent is never set to exactly the
spec limit for the power supply.
Takaman lists the G400 as 10 amps from 3.3V, but I expect
neither +3.3V or +5V to be limiting you here. (Your PCI
cards are chump change, in terms of power consumption.
I'm only trying to address the big consumers here, because
the small fry are too hard to guess at with any accuracy.)
The CD/DVD isn't going to draw power, unless you are booting
from a CD, and even then, the current profile of the
motor on the drive will not peak at the same time as
the hard drives. (And due to the optical disk industry
being very protective of their power numbers, we have no
real data to go on, other than the bogus 5V@1.5A 12V@1.5A
boiler plate numbers. All the optical drives out there
cannot be drawing exactly that same power number.)
I really don't see a reason to panic.
Have a look in your hardware monitor (or use a multimeter),
and see if the supply voltages are within 5% of their rated
values. If the +12V seems to be below 11.4V, then I'd consider
looking for another supply. A multimeter, connected to a
spare disk drive connector, will allow you to watch the +12V
voltage rail, during the 20 seconds it'll take to spin
up the disk drives.
AFAIK, those old Antec supplies are from HEC (I've got another
model, 352X), and the HEC supply I've got, doesn't seem to be
badly made.
So my guess would be, close to the limit on the +12V rail,
for the first 20 seconds, and comfortable the rest of the time.
Paul