Do I have a prayer?

  • Thread starter Thread starter Barry Watzman
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Barry Watzman

I have a situation in which there is need to run a system with a P4T-E
motherboard, 512 megs of RDRAM (4x128) and a Celeron 2.0GHz CPU from a
230 watt power supply that has only 8 amps of 12 volts. The case is
non-standard and neither it nor it's non-standard power supply can
easily be changed; the system currently has a P2B with an 850MHz
Celeron, but the P2B is dying.

Anyone think I have a prayer?

[other components: Soundblaster Audigy with live drive, ATI
All-in-Wonder Radeon 7500, network card, floppy, modem card, 2nd paralle
port card, one DVD-rom drive, WD1200JB 120 gig ide drive.]
 
Barry Watzman said:
I have a situation in which there is need to run a system with a P4T-E
motherboard, 512 megs of RDRAM (4x128) and a Celeron 2.0GHz CPU from a
230 watt power supply that has only 8 amps of 12 volts. The case is
non-standard and neither it nor it's non-standard power supply can
easily be changed; the system currently has a P2B with an 850MHz
Celeron, but the P2B is dying.

Anyone think I have a prayer?

[other components: Soundblaster Audigy with live drive, ATI
All-in-Wonder Radeon 7500, network card, floppy, modem card, 2nd paralle
port card, one DVD-rom drive, WD1200JB 120 gig ide drive.]
Click to expand...

From processorfinder.intel.com -

2.0Ghz Celeron = 53W 53W/12V=4.4 amps, 90% eff conversion = 4.9 amps.
1 amp @ 12V for fans, 0.5A @ 12V per drive device, gives a total
of 6.9 amps. The drives draw more current at startup, but the
processor probably isn't running at max then anyway.

The video card could likely be using lower voltages, as it has no
aux power connector. The ATI7500 shouldn't have an effect on +12V
(it doesn't need it, but any design decision by the card designer
is possible).

Total power demand for the box could be 130-150W under 100%
computing load, so it could work. It really depends on how the
board splits its load across +5V and +3.3V, compared to the
capacity of the supply on those two rails.

To give some examples:

P4C800-E Dlx, 2.8C processor, 4x512MB CAS2, ATI9800 (running Prime95)
1 HDD, 1 CDROM (video card power numbers are from another benchmark)

ATX12V(2x2 conn)=5.9A 3.3V=13.8A 5V=0.56A 12V(ATX20 conn)=0.43A
(ATI9800 max [email protected] [email protected], desktop [email protected] [email protected] or so)

Worst case 12V=7.2A, 3.3V=13.8A, 5V=6.1A ==> 162.4W

A7N8X-E Dlx, 11x200 mobile, 3x512MB CAS2, ATI9800 (running Prime95)
1 HDD, 1 CDROM

ATX12V(2x2 conn)=0 3.3V=5.5A 5V=15.9A 12V(ATX20 conn)=0.53A
(ATI9800 max [email protected] [email protected], desktop [email protected] [email protected] or so)

Worst case 12V=1.4A, 3.3V=5.5A, 5V=21.4A ==> 142W

As there is a tendency for older supplies to be a little more
honest about their output power, I would think you could get away
with it. Your ATI 7500 will draw less than half the power of the
ATI 9800, and the RDRAM might draw a slight bit more than the
DDR (just guessing that the serial I/O burns more power).

For a second opinion, go to the Intel web site, and see if
there is an Intel motherboard that uses RDRAM like your P4T-E.
Intel motherboard manuals usually have a section with power
estimates in it, and you could use those numbers to make your
decision too.

HTH,
Paul
 
Not a chance of doing it safely and not risking frying something (like the
motherboard) from driving the under-powered power supply into voltage
instability.
 
Barry Watzman said:
I have a situation in which there is need to run a system with a P4T-E
motherboard, 512 megs of RDRAM (4x128) and a Celeron 2.0GHz CPU from a
230 watt power supply that has only 8 amps of 12 volts. The case is
non-standard and neither it nor it's non-standard power supply can
easily be changed; the system currently has a P2B with an 850MHz
Celeron, but the P2B is dying.

Anyone think I have a prayer?

[other components: Soundblaster Audigy with live drive, ATI
All-in-Wonder Radeon 7500, network card, floppy, modem card, 2nd paralle
port card, one DVD-rom drive, WD1200JB 120 gig ide drive.]
Click to expand...

I don't agree that by running it near 100% capacity that you'll
destroy the power supply. Assuming that the cooling is adequate, the
supply should run just fine at its rated output. Almost every modern
switching power supply uses standard IC controllers that are designed
to protect the supply and the load under overload, or near overload
conditions. Now, having said that, I would agree that a poorly
designed supply could be running individual components at, or close to
their design limits and that could definitely shorten the life of the
supply. So, if the primary switching transistor is rated at 200Vce and
10A of current and at full load it is running at 200V and 10A, then I
agree that the supply will probably fail. However, if it is running at
50-75% of its limits, then it should work just fine.

arnie
 
Barry said:
I have a situation in which there is need to run a system with a P4T-E
motherboard, 512 megs of RDRAM (4x128) and a Celeron 2.0GHz CPU from a
230 watt power supply that has only 8 amps of 12 volts. The case is
non-standard and neither it nor it's non-standard power supply can
easily be changed; the system currently has a P2B with an 850MHz
Celeron, but the P2B is dying.
Click to expand...

I'm curious. Care to elaborate on "P2B is dying" ?

P2B

(alive and well ;-) )
Anyone think I have a prayer?

[other components: Soundblaster Audigy with live drive, ATI
All-in-Wonder Radeon 7500, network card, floppy, modem card, 2nd paralle
port card, one DVD-rom drive, WD1200JB 120 gig ide drive.]
Click to expand...
 
The system has become flakey in ways that suggest a possible motherboard
problem. I'm getting strange errors, I run chkdsk (without "/F", so it
doesn't actually fix anything), I get tons of cross-linked clusters. I
rerun it again immediately, and everything is fine (only, nothing has
changed).

Things like that. Ran a memory diagnostic, everything checks out,
memtest will run for hours. The problems appear to be disk related, but
I've tried two different drives, and different cables. So chipset?
Can't be sure, but that's what things point to.


Barry said:
I have a situation in which there is need to run a system with a P4T-E
motherboard, 512 megs of RDRAM (4x128) and a Celeron 2.0GHz CPU from a
230 watt power supply that has only 8 amps of 12 volts. The case is
non-standard and neither it nor it's non-standard power supply can
easily be changed; the system currently has a P2B with an 850MHz
Celeron, but the P2B is dying.
Click to expand...


I'm curious. Care to elaborate on "P2B is dying" ?

P2B

(alive and well ;-) )
Anyone think I have a prayer?

[other components: Soundblaster Audigy with live drive, ATI
All-in-Wonder Radeon 7500, network card, floppy, modem card, 2nd
paralle port card, one DVD-rom drive, WD1200JB 120 gig ide drive.]
Click to expand...
Click to expand...
 
Barry said:
The system has become flakey in ways that suggest a possible motherboard
problem. I'm getting strange errors, I run chkdsk (without "/F", so it
doesn't actually fix anything), I get tons of cross-linked clusters. I
rerun it again immediately, and everything is fine (only, nothing has
changed).

Things like that. Ran a memory diagnostic, everything checks out,
memtest will run for hours. The problems appear to be disk related, but
I've tried two different drives, and different cables. So chipset?
Can't be sure, but that's what things point to.
Click to expand...

I'd test it without PCI cards, and again with a known good power supply
(although you mentioned that's a problem in this 'case') before
condemning the motherboard... just a hunch ;-)

P2B
P2B said:
Barry said:
I have a situation in which there is need to run a system with a
P4T-E motherboard, 512 megs of RDRAM (4x128) and a Celeron 2.0GHz CPU
from a 230 watt power supply that has only 8 amps of 12 volts. The
case is non-standard and neither it nor it's non-standard power
supply can easily be changed; the system currently has a P2B with an
850MHz Celeron, but the P2B is dying.
Click to expand...



I'm curious. Care to elaborate on "P2B is dying" ?

P2B

(alive and well ;-) )
Anyone think I have a prayer?

[other components: Soundblaster Audigy with live drive, ATI
All-in-Wonder Radeon 7500, network card, floppy, modem card, 2nd
paralle port card, one DVD-rom drive, WD1200JB 120 gig ide drive.]
Click to expand...
Click to expand...
Click to expand...
 
The system has become flakey in ways that suggest a possible motherboard
problem. I'm getting strange errors, I run chkdsk (without "/F", so it
doesn't actually fix anything), I get tons of cross-linked clusters. I
rerun it again immediately, and everything is fine (only, nothing has
changed).

Things like that. Ran a memory diagnostic, everything checks out,
memtest will run for hours. The problems appear to be disk related, but
I've tried two different drives, and different cables. So chipset?
Can't be sure, but that's what things point to.
Click to expand...


Could also be the power supply. I'd run the machine with a known good
supply even if it meant leaving the cover off for a few days.
 
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