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Power supply adivice needed



 
 
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  #1  
Old February 5th 11, 07:49 AM posted to alt.comp.hardware.pc-homebuilt
Ray
external usenet poster
 
Posts: 6
Default Power supply adivice needed

Ray wrote:
I have a ASUS P5B-E mo, a GeForce 9500 GT video, 4 sata hard drives (with
sata and Molex connectors) and 5 usb peripherals and need a power supply

to
run it. The GF9500GT video card wants 18 amps so I am thinking of getting
one of these supplies:
1. OXZ OCZ500MXSP

http://www.newegg.com/Product/Produc...6&Tpk=OCZ500MX
SP
2. CoolerMaster RS-460-PSAR-J3

http://www.newegg.com/Product/Produc...6&cm_re=RS-460
-PSAR-J3-_-17-171-046-_-Product
3. CoolerMaster RS-500 PCAR-A3-US

http://www.newegg.com/Product/Produc...1&Tpk=rs-500pc
ar-a3-us
I like the idea of the modular wiring with the OCZ supply but was

wondering
if the relatively low -5v (.3a) is a possible problem. This one is more
efficient too and has lots of connections but, of course, costs more.


My question is: Which one is the best fit for my computer? Or if you

think
there are better choices with about the same cost, what would you suggest?


Thanks,
Ray


Opps, I made a mistake and wrote "-5v" when I meant -12v. It seems most
supplies have 0.8 amp for the -12v line. Should have typed "1. OCZ" (not
OXZ) also.

I guess I'm dizzy from looking at so many specs and comments. I didn't
remember the ones for the CoolerMaster supplies. I did see the comments for
the OCZ but they looked better than a lot of others I've seen. I had a
EnerMax 420W supply but it broke down after a few years and that is why I
need a new supply. It also seemed to be somewhat under powered for my
system too. I have an Intel Core 2 Duo E6400 CPU. The GeForce 9500GT
(PCI-E but no separate power connector) spec sheet says a minimum of 350 W
power supply with a min recommended +12v current rating of 18 amps. so I
assume that means for that power rail that supports the mob. Isn't this
right?

I have been trying to find supplies with +12v rails supporting 18 amps and
there don't seem to be many under $100. Any suggestions?

Ray



  #2  
Old February 5th 11, 08:39 AM posted to alt.comp.hardware.pc-homebuilt
Paul
external usenet poster
 
Posts: 13,364
Default Power supply adivice needed

Ray wrote:
Ray wrote:
I have a ASUS P5B-E mo, a GeForce 9500 GT video, 4 sata hard drives (with
sata and Molex connectors) and 5 usb peripherals and need a power supply

to
run it. The GF9500GT video card wants 18 amps so I am thinking of getting
one of these supplies:
1. OXZ OCZ500MXSP

http://www.newegg.com/Product/Produc...6&Tpk=OCZ500MX
SP
2. CoolerMaster RS-460-PSAR-J3

http://www.newegg.com/Product/Produc...6&cm_re=RS-460
-PSAR-J3-_-17-171-046-_-Product
3. CoolerMaster RS-500 PCAR-A3-US

http://www.newegg.com/Product/Produc...1&Tpk=rs-500pc
ar-a3-us
I like the idea of the modular wiring with the OCZ supply but was

wondering
if the relatively low -5v (.3a) is a possible problem. This one is more
efficient too and has lots of connections but, of course, costs more.


My question is: Which one is the best fit for my computer? Or if you

think
there are better choices with about the same cost, what would you suggest?


Thanks,
Ray


Opps, I made a mistake and wrote "-5v" when I meant -12v. It seems most
supplies have 0.8 amp for the -12v line. Should have typed "1. OCZ" (not
OXZ) also.

I guess I'm dizzy from looking at so many specs and comments. I didn't
remember the ones for the CoolerMaster supplies. I did see the comments for
the OCZ but they looked better than a lot of others I've seen. I had a
EnerMax 420W supply but it broke down after a few years and that is why I
need a new supply. It also seemed to be somewhat under powered for my
system too. I have an Intel Core 2 Duo E6400 CPU. The GeForce 9500GT
(PCI-E but no separate power connector) spec sheet says a minimum of 350 W
power supply with a min recommended +12v current rating of 18 amps. so I
assume that means for that power rail that supports the mob. Isn't this
right?

I have been trying to find supplies with +12v rails supporting 18 amps and
there don't seem to be many under $100. Any suggestions?

Ray


The value the video card advertising recommends, is based on some assumptions
about the contents of your computer case. The assumptions may not be valid.

Let's try some numbers.

E6400 = 65W. 65W/12V * 1/0.90 = 12V @ 6 amps from 12V2 rail, (90% Vcore efficiency)

http://ark.intel.com/Product.aspx?id...T9,SL9TY,SLA97

The rest of the loads will be from 12V1.

(4) hard drives. While idle in desktop, 0.6 amps each.
Total 12V @ 2.4A from 12V1. When the hard drives spin up,
the current is 2.5A for each drive, or about 10A total.
When there are enough drives, a separate calculation should be
carried out. Four drives happens to be the limit, before a person
should calculate startup power requirements. Many supplies
can withstand an overage on current during startup, but if
you have enough hard drives, the startup current can crush the
supply, and OC shuts off the power before the computer can POST.
Overcurrent detection on an ATX supply, is likely disabled for the
first 35 milliseconds, but is enabled from then on.

(1) CDROM. About 12V @ 1.5A boiler plate rating. I've measured 12V @ 1.0A
while media was spinning at top speed. This is from 12V1. If you have
no media in the tray, the current is zero.

(1) 9500 GT. 12V @ 4A approx from 12V1.

(x) Cooling fans. Guess 12V @ 0.5A as an estimated total. Read the
current rating on each fan hub, for an exact number. From 12V1 rail.

Total so far, at idle in the desktop

12V2 @ 6 amps CPU
12V1 @ 2.4+1.5+4.0+0.5 = 12V1 @ 8.4A HDD/ODD/video/fans

That's a total of 14.4 amps from both rails.

If we look at startup current, for the first ten seconds, the
processor is not running full power. The number is less. The BIOS
might be using one core. So this would be during the first 10 seconds.
The video card is also not at max power, because it isn't in 3D mode.
We'll cut the power on that in half as well (if Xbitlabs had numbers,
I could provide actual values for this).

12V2 @ 3 amps CPU
12V1 @ 10.0+1.5+2.0+0.5 = 12V1 @ 14A HDD/ODD/video/fans

In terms of total system power (watts), I need to include some 5V current
for the HDD and ODD. 5V @ 1A per hard drive. 5V @ 1.5A for optical.
Also, I include 50W for motherboard chipset and RAM DIMMs. Some DIMMs
now, are 2W each. Include 10W for +5VSB to power USB bus devices.
I use the "long term power" numbers for this calculation, with CPU
at full power, video card at full power.

12V * (6+8.4A) + 4*5*1 + 1*5*1.5 + 50 + 10 =
172.8 + 20 + 7.5 + 50 + 10 = 260.3W

so that would be an upper limit. I have an Intel processor here,
that is rated at 65W, that won't draw more than 36W under actual
usage, so the number on a real system is likely lower than the
260W I just calculated.

I just bought this yesterday, but the shipper hasn't delivered it
yet. This is to give you an example of how cheaply you can meet the
numbers.

http://images17.newegg.com/is/image/newegg/17-103-013-S03?$S640W$

http://www.newegg.com/Product/Produc...82E16817103013

3.3V @ 30A
5V @ 28A
12V1 @ 18A (enough to not only spin up the drives, but run continuously at that level)
12V2 @ 18A (plenty for just the processor)
+5VSB @ 2A (not a lot, but sufficient. May require unplugging some USB if there is trouble)
-12V @ 0.5A (don't care...)

(3.3V & 5V = 150W max) compare to 50W + 4*5*1 + 1*5*1.5 = 77.5W
(12V1 & 12V2 = 348W max) compare to our 172.8W figure, about half load
(DC output 400W) compare to 260W calculated

The supply meets our needs.

And that power supply is $45. I'm putting that power supply in
my oldest system, so I can move a better supply up into another
computer. The supply is likely not going to meet 80% efficiency,
so I wouldn't necessarily want to be running it 24 hours per day.
The better supply, has a higher efficiency, so I can afford to
leave it running if necessary. Another advantage of that SPI supply,
is no Active PFC, so no nasty reactions to my UPS switching to
battery operation.

I suspect my UPS makes the red waveform shown in this picture,
when the UPS is running from battery, and that little SPI supply
has no power factor correction, to get tied in knots by a square wave.
The core of an ATX supply, doesn't care that the AC waveform is a
square wave, but the recently introduced Active PFC on power supplies
(which sits in front of the regular ATX power supply design), does
care about waveshape, as the Active PFC reacts to waveshape in an
attempt to correct it. So far, I have *no* active PFC supplies
in the house. It's not that I don't like Active PFC, merely that
it isn't that compatible with my ancient UPS.

http://i285.photobucket.com/albums/l...ppedPure-1.jpg

You can certainly cure that problem, with a purer sine wave UPS, but
I really don't have the money to waste on that. Even if my UPS died
tomorrow (and it may), based on economics, all I could afford is
another square wave one. So I can't afford to buy any Active PFC
ATX supplies, and find out the combination is not happy. Sometimes, you
can spot those problems, by reading reviews on Newegg, for an
Active PFC supply.

This is a short blog on PFC, which doesn't show what happens. But
it does warn about mixing them.

http://www.dougv.com/blog/2010/03/01...t-low-end-ups/

"This I learned the hard way, as my Antec EarthWatts EA 500 PSU,
which I adore, will go dead the second the battery on my APC
Back-UPS BX1300LCD kicks in."

And that behavior, kinda negates why we have UPSes on computers :-)
My UPS is there, primarily to cover the one second outages we get
here, rather than power the computer for a couple hours.

HTH,
Paul
  #3  
Old February 5th 11, 05:53 PM posted to alt.comp.hardware.pc-homebuilt
GMAN[_13_]
external usenet poster
 
Posts: 403
Default Power supply adivice needed

In article , "Ray" wrote:
Ray wrote:
I have a ASUS P5B-E mo, a GeForce 9500 GT video, 4 sata hard drives (with
sata and Molex connectors) and 5 usb peripherals and need a power supply

to
run it. The GF9500GT video card wants 18 amps so I am thinking of getting
one of these supplies:
1. OXZ OCZ500MXSP

http://www.newegg.com/Product/Produc...6&Tpk=OCZ500MX
SP
2. CoolerMaster RS-460-PSAR-J3

http://www.newegg.com/Product/Produc...6&cm_re=RS-460
-PSAR-J3-_-17-171-046-_-Product
3. CoolerMaster RS-500 PCAR-A3-US

http://www.newegg.com/Product/Produc...1&Tpk=rs-500pc
ar-a3-us
I like the idea of the modular wiring with the OCZ supply but was

wondering
if the relatively low -5v (.3a) is a possible problem. This one is more
efficient too and has lots of connections but, of course, costs more.


My question is: Which one is the best fit for my computer? Or if you

think
there are better choices with about the same cost, what would you suggest?


Thanks,
Ray


Opps, I made a mistake and wrote "-5v" when I meant -12v. It seems most
supplies have 0.8 amp for the -12v line. Should have typed "1. OCZ" (not
OXZ) also.

I guess I'm dizzy from looking at so many specs and comments. I didn't
remember the ones for the CoolerMaster supplies. I did see the comments for
the OCZ but they looked better than a lot of others I've seen. I had a
EnerMax 420W supply but it broke down after a few years and that is why I
need a new supply. It also seemed to be somewhat under powered for my
system too. I have an Intel Core 2 Duo E6400 CPU. The GeForce 9500GT
(PCI-E but no separate power connector) spec sheet says a minimum of 350 W
power supply with a min recommended +12v current rating of 18 amps. so I
assume that means for that power rail that supports the mob. Isn't this
right?

I have been trying to find supplies with +12v rails supporting 18 amps and
there don't seem to be many under $100. Any suggestions?

Ray




For my own builds i never go less than a 600Watt supply and i am very hooked
on the Modular type supplies. I love the fact that you only use what cables
you need. If say my system has only SATA drives and no old EIDE drives, why
have 6-8 old Molex plugs on a pair of 2 foot cords all messing up the inside
of my case??????
  #4  
Old February 5th 11, 08:04 PM posted to alt.comp.hardware.pc-homebuilt
Ray
external usenet poster
 
Posts: 6
Default Power supply adivice needed

"GMAN" wrote in message
...
In article , "Ray"

wrote:
Ray wrote:
I have a ASUS P5B-E mo, a GeForce 9500 GT video, 4 sata hard drives

(with
sata and Molex connectors) and 5 usb peripherals and need a power

supply
to
run it. The GF9500GT video card wants 18 amps so I am thinking of

getting
one of these supplies:
1. OXZ OCZ500MXSP

(skip)
Opps, I made a mistake and wrote "-5v" when I meant -12v. It seems most
supplies have 0.8 amp for the -12v line. Should have typed "1. OCZ" (not
OXZ) also.

I guess I'm dizzy from looking at so many specs and comments. I didn't
remember the ones for the CoolerMaster supplies. I did see the comments

for
the OCZ but they looked better than a lot of others I've seen. I had a
EnerMax 420W supply but it broke down after a few years and that is why I
need a new supply. It also seemed to be somewhat under powered for my
system too. I have an Intel Core 2 Duo E6400 CPU. The GeForce 9500GT
(PCI-E but no separate power connector) spec sheet says a minimum of 350

W
power supply with a min recommended +12v current rating of 18 amps. so I
assume that means for that power rail that supports the mob. Isn't this
right?

I have been trying to find supplies with +12v rails supporting 18 amps

and
there don't seem to be many under $100. Any suggestions?

Ray




For my own builds i never go less than a 600Watt supply and i am very

hooked
on the Modular type supplies. I love the fact that you only use what

cables
you need. If say my system has only SATA drives and no old EIDE drives,

why
have 6-8 old Molex plugs on a pair of 2 foot cords all messing up the

inside
of my case??????


I like the modular concept too but in actual use don't know if it would save
me much cabling anyway - I need both SATA and Molex anyway. It would
eliminate the PCI-E cable since I don't do SLI. Maybe nice when I have to
change components. From what I see and have read, the wattage ratings don't
tell much - it's the current ratings for the needed voltage rails that
counts. As I mentioned, I have a problem finding the 18 amp +12v line for
the graphics card. Also worried about enough current for the HD/DVD/CD
drives and USB.




  #5  
Old February 5th 11, 08:20 PM posted to alt.comp.hardware.pc-homebuilt
Ray
external usenet poster
 
Posts: 6
Default Power supply adivice needed

"Paul" wrote in message
...
Ray wrote:
Ray wrote:
I have a ASUS P5B-E mo, a GeForce 9500 GT video, 4 sata hard drives

(with
sata and Molex connectors) and 5 usb peripherals and need a power

supply
to
run it. The GF9500GT video card wants 18 amps so I am thinking of

getting
one of these supplies:
1. OXZ OCZ500MXSP
(skip)
there are better choices with about the same cost, what would you

suggest?

Thanks,
Ray


Opps, I made a mistake and wrote "-5v" when I meant -12v. It seems most
supplies have 0.8 amp for the -12v line. Should have typed "1. OCZ"

(not
OXZ) also.

I guess I'm dizzy from looking at so many specs and comments. I didn't
remember the ones for the CoolerMaster supplies. I did see the comments

for
the OCZ but they looked better than a lot of others I've seen. I had a
EnerMax 420W supply but it broke down after a few years and that is why

I
need a new supply. It also seemed to be somewhat under powered for my
system too. I have an Intel Core 2 Duo E6400 CPU. The GeForce 9500GT
(PCI-E but no separate power connector) spec sheet says a minimum of 350

W
power supply with a min recommended +12v current rating of 18 amps. so I
assume that means for that power rail that supports the mob. Isn't this
right?

I have been trying to find supplies with +12v rails supporting 18 amps

and
there don't seem to be many under $100. Any suggestions?

Ray


The value the video card advertising recommends, is based on some

assumptions
about the contents of your computer case. The assumptions may not be

valid.

Let's try some numbers.

E6400 = 65W. 65W/12V * 1/0.90 = 12V @ 6 amps from 12V2 rail, (90% Vcore

efficiency)


http://ark.intel.com/Product.aspx?id...ec-codes=SL9S9,
SL9T9,SL9TY,SLA97

The rest of the loads will be from 12V1.

(4) hard drives. While idle in desktop, 0.6 amps each.
Total 12V @ 2.4A from 12V1. When the hard drives spin up,
the current is 2.5A for each drive, or about 10A total.
When there are enough drives, a separate calculation should be
carried out. Four drives happens to be the limit, before a person
should calculate startup power requirements. Many supplies
can withstand an overage on current during startup, but if
you have enough hard drives, the startup current can crush the
supply, and OC shuts off the power before the computer can POST.
Overcurrent detection on an ATX supply, is likely disabled for the
first 35 milliseconds, but is enabled from then on.

(1) CDROM. About 12V @ 1.5A boiler plate rating. I've measured 12V @ 1.0A
while media was spinning at top speed. This is from 12V1. If you have
no media in the tray, the current is zero.

(1) 9500 GT. 12V @ 4A approx from 12V1.

(x) Cooling fans. Guess 12V @ 0.5A as an estimated total. Read the
current rating on each fan hub, for an exact number. From 12V1 rail.

Total so far, at idle in the desktop

12V2 @ 6 amps CPU
12V1 @ 2.4+1.5+4.0+0.5 = 12V1 @ 8.4A HDD/ODD/video/fans

That's a total of 14.4 amps from both rails.

If we look at startup current, for the first ten seconds, the
processor is not running full power. The number is less. The BIOS
might be using one core. So this would be during the first 10 seconds.
The video card is also not at max power, because it isn't in 3D mode.
We'll cut the power on that in half as well (if Xbitlabs had numbers,
I could provide actual values for this).

12V2 @ 3 amps CPU
12V1 @ 10.0+1.5+2.0+0.5 = 12V1 @ 14A HDD/ODD/video/fans

In terms of total system power (watts), I need to include some 5V current
for the HDD and ODD. 5V @ 1A per hard drive. 5V @ 1.5A for optical.
Also, I include 50W for motherboard chipset and RAM DIMMs. Some DIMMs
now, are 2W each. Include 10W for +5VSB to power USB bus devices.
I use the "long term power" numbers for this calculation, with CPU
at full power, video card at full power.

12V * (6+8.4A) + 4*5*1 + 1*5*1.5 + 50 + 10 =
172.8 + 20 + 7.5 + 50 + 10 = 260.3W

so that would be an upper limit. I have an Intel processor here,
that is rated at 65W, that won't draw more than 36W under actual
usage, so the number on a real system is likely lower than the
260W I just calculated.


Looks like my response didn't get to the newsgroup so I'll repeat it here.
Sorry if it shows up twice.

Thanks for the detailed analysis. I forgot to mention an additional tray
mounted HD and I have a DVD as well as a CD drive but those should fit in
without much additional current demands. I like the modular designs and
would like to find a supply that has sufficient ASATA and Molex connetors to
handle my loads without a lot of extentions needed. I'll take a look at the
supply you mention below. Except for cables, it seems to handle enough
currents. Thanks again.

I just bought this yesterday, but the shipper hasn't delivered it
yet. This is to give you an example of how cheaply you can meet the
numbers.

http://images17.newegg.com/is/image/newegg/17-103-013-S03?$S640W$

http://www.newegg.com/Product/Produc...82E16817103013

3.3V @ 30A
5V @ 28A
12V1 @ 18A (enough to not only spin up the drives, but run

continuously at that level)
12V2 @ 18A (plenty for just the processor)
+5VSB @ 2A (not a lot, but sufficient. May require unplugging some

USB if there is trouble)
-12V @ 0.5A (don't care...)

(3.3V & 5V = 150W max) compare to 50W + 4*5*1 + 1*5*1.5 = 77.5W
(12V1 & 12V2 = 348W max) compare to our 172.8W figure, about half load
(DC output 400W) compare to 260W calculated

The supply meets our needs.

And that power supply is $45. I'm putting that power supply in
my oldest system, so I can move a better supply up into another
computer. The supply is likely not going to meet 80% efficiency,
so I wouldn't necessarily want to be running it 24 hours per day.
The better supply, has a higher efficiency, so I can afford to
leave it running if necessary. Another advantage of that SPI supply,
is no Active PFC, so no nasty reactions to my UPS switching to
battery operation.

I suspect my UPS makes the red waveform shown in this picture,
when the UPS is running from battery, and that little SPI supply
has no power factor correction, to get tied in knots by a square wave.
The core of an ATX supply, doesn't care that the AC waveform is a
square wave, but the recently introduced Active PFC on power supplies
(which sits in front of the regular ATX power supply design), does
care about waveshape, as the Active PFC reacts to waveshape in an
attempt to correct it. So far, I have *no* active PFC supplies
in the house. It's not that I don't like Active PFC, merely that
it isn't that compatible with my ancient UPS.

http://i285.photobucket.com/albums/l...ppedPure-1.jpg

You can certainly cure that problem, with a purer sine wave UPS, but
I really don't have the money to waste on that. Even if my UPS died
tomorrow (and it may), based on economics, all I could afford is
another square wave one. So I can't afford to buy any Active PFC
ATX supplies, and find out the combination is not happy. Sometimes, you
can spot those problems, by reading reviews on Newegg, for an
Active PFC supply.

This is a short blog on PFC, which doesn't show what happens. But
it does warn about mixing them.


http://www.dougv.com/blog/2010/03/01...re-not-compata
ble-with-most-low-end-ups/

"This I learned the hard way, as my Antec EarthWatts EA 500 PSU,
which I adore, will go dead the second the battery on my APC
Back-UPS BX1300LCD kicks in."

And that behavior, kinda negates why we have UPSes on computers :-)
My UPS is there, primarily to cover the one second outages we get
here, rather than power the computer for a couple hours.

HTH,
Paul



 




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