850 watt PSU overkill for this setup...?


M

markm75

I currently have a 600 watt PSU.. was considering going to an 850
watt, i dont have the 4 extra drives, the 8800gtx just yet (using
8600gt and 7600gt right now)...

**Adding soon

CPU.. 2.4 GHZ quad core
RAM: 4GB
USB: 12-13 (maybe 8 simultaneously)
***Video: pcie x16 Geforce 8800GTX 768 MB
Video2: pcie x16 Geforce 8600GT 256MB (non sli)
PCIe x 4: usb card

PCI = usb card
PCI = Video capture

3, 5.25" removable drive bays (sataII drives)

esata: one external
one 3.5" card reader (usb on the one card)
1 Bluray reader

**Adding pcie x8 controller card for, 4 more internal SATAII drives,
raid0.


Any thoughts on if this spec means i should shoot for 850 watt? I've
looked at the online calculators.. i'm not sure whether its accurate
or not.. but i think with the extra 4 harddrives it suggested 660
watts or so.. without the 4 drives, maybe 590 even with the GTX, but i
dont think that took into account the 2nd 8600gt...

I'm guessing 850 may be over kill even with the 4 drives and gtx?
Perhaps 700 is a better bet, but if i ever decide to go sli, the 850
is a must i'm sure?

Thanks in advance
 
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M

markm75

I currently have a 600 watt PSU.. was considering going to an 850
watt, i dont have the 4 extra drives, the 8800gtx just yet (using
8600gt and 7600gt right now)...

**Adding soon

CPU.. 2.4 GHZ quad core
RAM:  4GB
USB:  12-13  (maybe 8 simultaneously)
***Video:  pcie x16   Geforce 8800GTX 768 MB
Video2:  pcie x16 Geforce 8600GT 256MB (non sli)
PCIe x 4:  usb card

PCI = usb card
PCI = Video capture

3, 5.25" removable drive bays (sataII drives)

esata:  one external
one 3.5" card reader (usb on the one card)
1 Bluray reader

**Adding pcie x8 controller card for, 4 more internal SATAII drives,
raid0.

Any thoughts on if this spec means i should shoot for 850 watt?  I've
looked at the online calculators.. i'm not sure whether its accurate
or not.. but i think with the extra 4 harddrives it suggested 660
watts or so.. without the 4 drives, maybe 590 even with the GTX, but i
dont think that took into account the 2nd 8600gt...

I'm guessing 850 may be over kill even with the 4 drives and gtx?
Perhaps 700 is a better bet, but if i ever decide to go sli, the 850
is a must i'm sure?

Thanks in advance

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
 
P

Paul

markm75 said:
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 - 131W
http://www.xbitlabs.com/images/video/msi8800gts-640/8800gtx_full.gif

8600GTS - 47W
http://www.xbitlabs.com/articles/video/display/geforce8600gts_7.html
http://www.xbitlabs.com/images/video/geforce8600gts/8600gts_power_full.gif

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 - 131W
http://www.xbitlabs.com/images/video/msi8800gts-640/8800gtx_full.gif

8600GTS - 47W
http://www.xbitlabs.com/images/video/geforce8600gts/8600gts_power_full.gif

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-38...ower-pro-850w-netzteil-review-rs-850-emba.htm

(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|en&u=
http://www.technic3d.com/article-38...l-review-rs-850-emba.htm&prev=/language_tools

HTH,
Paul
 
M

markm75

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 -

That was an awesome breakdown.. thanks much.. ill have to take some
notes later.. but in quick reading it sounds like 600watts was enough
even with both video cards (non sli) and all the drives..
 
P

Paul

markm75 said:
That was an awesome breakdown.. thanks much.. ill have to take some
notes later.. but in quick reading it sounds like 600watts was enough
even with both video cards (non sli) and all the drives..

It looks like it. The thing is, the label on the side of the supply,
has multiple limits listed on it, some interfering with other
limits. The trick is to try to take all of them into account.
So not just any 600W supply would necessarily do (like some $20
supply).

Some, for example, might list 12V @ 18A on each of four outputs.
Then, they list a "480W" limit for all the 12V outputs combined.
You can then think of that as 12V @ 40A spread over four outputs,
which isn't quite the same as 18A. The 18A number can be achieved,
if a particular output is heavily loaded, say two of them, but
then you couldn't really load three or four of them heavily.
In that case, the 480W combined power limit is just as important
to satisfy, as the 12V @ 18A on each individual output.

In selecting a supply, if you know it is going to run at 455W
a lot of the time, it is good to have an efficient supply as well.
For example, your 850W unit has 85% efficiency. The efficiency
changes a bit, with output loading, so the efficiency is not
uniform across all loads. But if we assumed it was for a moment,
then 455/0.85 - 455 = 80W of heat is created by the supply itself.
If you purchased a supply which was only 68% efficient (a number
common to cheap supplies), then 455/0.68 - 455 = 214W. That makes
a difference to how hot the supply runs, and to the fan speed it
needs to remain cool.

In addition to the specsmanship, you should also read the reviews
on Newegg. A lot of the supplies will be listed on there, and it
is a good idea to check there, to see if the design you want to buy
is a dud or not. Jonnyguru.com also has quite a few reviews, and
evaluates ripple and voltage output, using a proper tester.

Paul
 
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T

Timothy Daniels

Power supplies are such an area for manufacturers'
"specsmanship" that choices become such a shot in
the dark. Thanks again for your writeup.

*TimDaniels*
 

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