As an aside.. i was considering this unit.. as its the cheapest i've
found at $129 :
http://www.svc.com/rs-850-emba.html COOLER MASTER RS-850-EMBA The
reviews seem solid enough
Video cards have idle, 2D peak, and 3D peak measurements. Sitting in the
BIOS would be idle. Gaming would be 3D peak, but I don't know if both your
cards run in 3D mode, if you game on that machine. Also, I don't have a
figure for 8600GT, but the 8600GTS shows that the power is low anyway.
8800GTX - 131Whttp://
www.xbitlabs.com/images/video/msi8800gts-640/8800gtx_full.gif
8600GTS - 47Whttp://
www.xbitlabs.com/articles/video/dis...images/video/geforce8600gts/8600gts_power_ful....
A video card has two or three power sources. The 8800GTX has two
aux connectors, as well as the PCI Express slot. Current flows in
each of those, and happens to be roughly equal. When computing the
current per rail, you have to figure out where each of those sources
are coming from. So if you buy a supply with "six output rails", it
means working the current drain on each of them. Some supplies
have individual rail specs, and unequal limits. And we're not
really sure, whether the supply has true independent outputs,
or in fact all the current is coming from one transformer anyway.
In some cases, the individual "rails" are being enforced by overcurrent
circuits, and that is the sum total of individuality.
PCpowerandcooling.com has some supplies, where the 12V rail is one big output,
and has a combined current spec. That at least, makes it a bit easier to
work out whether the supply has enough power.
Since you have seven hard drives, then that requires working out power
consumption at two points in system operation. The first condition is
during hard drive spinup. Some drives now, take 2.5A from 12V, during
drive spinup. 7 * 2.5A = 17.5A for the first 10 seconds, from whatever
rail they are connected to. During that same point in time, video cards
draw idle power (a big improvement) and the processor might be running
at half power (based on measurements on my older systems - no idea how
modern systems work during the BIOS interval). Certainly the BIOS is
not multicore aware, and won't run all cores 100% anyway, so I suppose
less than full power is a safe assumption.
First, a total system power check. Assume, right or wrong, that the
two video cards are at peak 3D level.
8800GTX - 131Whttp://
www.xbitlabs.com/images/video/msi8800gts-640/8800gtx_full.gif
8600GTS - 47Whttp://
www.xbitlabs.com/images/video/geforce8600gts/8600gts_power_ful...
7 hard drives - about 7*13W = 91W with disks idle in the desktop.
bluray player - Sample numbers for a Pioneer = +5V 1.25A +12V 1.6A
- 12V power mainly when media is present
quad core - depends on chip family - 95W is possible
motherboard+ram - allocate 50W (based on previous measurements - no calc possible)
fans - 12V @ 0.5A (or look on the label of all the fans)
+5VSB rail - 5 to 10W in standby, or for USB etc.
Rough total power estimate (gaming) -
131 + 47 + 91 + 25.45 + 95 + 50 + 6 + 10 = 455.45W
Now some current numbers for the 12V rail(s).
Spinup:
I'm using video card idle power, and only on the 12V rail. Spinup
current on the disk drives. Bluray player has media in it, so motor is on.
Processor is at half power, and is powered by a 90% efficient Vcore circuit.
The motherboard doesn't draw any 12V current, except for fans plugged to
the fan headers, and those are estimated here as 0.5A. Current on 12V is -
63/12 + 19.6/12 + (7 * 2.5amps) + 1.6A + (95/2/0.9)/12 + 0.5 =
5.25 + 1.63 + 17.5 + 1.6A + 4.4 + 0.5 = 30.88A
Gaming:
Video cards assumed in 3D peak (only 12V rail power used for the calc).
Hard drives are spinning but idle. Bluray disk spinning. Processor at
full power and Vcore is 90% efficient. Current on 12V is -
127.6/12 + 45.35/12 + (7 * 0.6amps) + 1.6A + (95/0.9)/12 + 0.5A =
10.63 + 3.78 + 4.2 + 1.6A + 8.8 + 0.5 = 29.51A
So spinup and gaming are pretty close to one another.
We need a supply with at least 455W total power. And a combined
12V rail of 31 amps. A Silencer 610W fills the bill. (It doesn't have
enough PCI Express connectors on it, to be really flexible - two
might be enough to suit the 8800GTX. Leaving zero extra ones.) The
single 12V rail is rated at 49 amps, more than enough for the 31 amp
load. The 3.3V and 5V rail shouldn't have a problem with the 50W
motherboard, plus 7 * 1A for hard drives, and 1 * 1.25A for Bluray.
http://www.pcpower.com/downloads/specs_3825.pdf
A supply with four PCI Express connectors is better suited to a
large SLI setup, but costs a bit more. The Silencer 750W has
four PCI Express connectors. And so much 12V rating, you could
run a bunch more hardware from it.
http://www.pcpower.com/downloads/specs_3827.pdf
The connector split on the Coolermaster can be seen here. 12V1 is used
for motherboard - meaning it provides PCI Express slot power (~3.5A * 2
in an SLI case + 0.5A fans). 12V2 powers the processor via the 2x2 connector.
12V3,12V4,12V5,12V6 are used for PCI Express. SATA drives are on
12V6, IDE drives on 12V5. The combined limit on all 12V, is 64 amps,
and whether the load is 31 amps (or 38 amps with 2*8800GTX), there
shouldn't be a problem there.
Real Power Pro 850W [RS-850-EMBA]
http://www.coolermaster.com/uploads/support/file1192156083173.pdf
(850W reviewed here - page 6 gives the measured overcurrent limits)
http://www.technic3d.com/article-389,1-sechsgleisig-coolermaster-real...
(Translated to English - manual line wrap due to USENET line length limit)
http://64.233.179.104/translate_c?hl=de&ie=UTF-8&oe=UTF-8&langpair=de...
http://www.technic3d.com/article-389,1-sechsgleisig-coolermaster-real...
HTH,
Paul- Hide quoted text -
- Show quoted text -
