Stange problem

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Larc

A Pentium III 866 CPU I have refuses to operate with a 250W PS. It wants 300W
or better. Yet, a PIII 1G CPU operates with no problem with the 250W PS. I've
checked these two CPUs in three different motherboards. Same story. Anybody
have any idea what's going on? I always thought the faster CPU would be pickier
about the PS.

Larc



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Are you just installing the basics when trying the 1G cpu with the 250w PSU?
(CPU,vid,memory) or is it just a swap of CPU's it the same machine. Are both
CPU flipchips or is one slot 1?
 
well that is a weird one.... two seperate INTEL chips in the same machine If
it were an AMD I could see the problem....I guess the only thing to do is
use the 300w PSU
 
Larc said:
| Are you just installing the basics when trying the 1G cpu with the 250w PSU?
| (CPU,vid,memory) or is it just a swap of CPU's it the same machine. Are both
| CPU flipchips or is one slot 1?

Both are socket 370. Minimum hardware connected. No differences in setup. The
PIII 1G will run with a 250W PS (I've tried two different 250W units), but the
866 won't. Both will run with a 300W PS.

Technically, 250W should be enough for the 866. But the chip evidently doesn't
know that.

Larc



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Click to expand...


Interesting problem. There was a P3-1Gz (BX80530C1000256) which took 1.5v
but all P3-866 socket 370 take 1.7v.
My guess is your 250 only supplies 5.5v on the +12v line which supplies
power to hd, mb, psu and fans. So that 0.2v difference doesn't boot the pc.
I researched that stuff when I noticed the psu powering a Cel 333 was only
200w yet the psu powered cd,dvd, pci nic, 1-3 hds, usb scanner, onboard agp
and sound.

http://processorfinder.intel.com/scripts/list.asp?ProcFam=25&CorSpd=ALL&SysB
usSpd=ALL&PkgType=ALL
 
| Interesting problem. There was a P3-1Gz (BX80530C1000256) which took 1.5v
| but all P3-866 socket 370 take 1.7v.
| My guess is your 250 only supplies 5.5v on the +12v line which supplies
| power to hd, mb, psu and fans. So that 0.2v difference doesn't boot the pc.
| I researched that stuff when I noticed the psu powering a Cel 333 was only
| 200w yet the psu powered cd,dvd, pci nic, 1-3 hds, usb scanner, onboard agp
| and sound.
|
| http://processorfinder.intel.com/scripts/list.asp?ProcFam=25&CorSpd=ALL&SysBusSpd=ALL&PkgType=ALL

I was hoping you might have pinpointed the problem, but it looks as if the ? is
still there. The 1GHz CPU (actually 1.13GHz I now find out) is firmly planted
in a motherboard under Arctic Silver, heatsink and fan, so I didn't want to dig
it out to check the specific model. But SiSoft Sandra reports its core voltage
at 1.75. So that's evidently not the answer.

I'm beginning to suspect that I may just have a slightly faulty 866 Pentium. A
friend was using it before he got me to build him a P4 2.4GHz system. He had
been having occasional problems even with a 300W PSU. I was never able to find
a definite cause, but I suppose it could have been the CPU.

Thanks for your help anyway.

Larc



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Larc said:
| Interesting problem. There was a P3-1Gz (BX80530C1000256) which took 1.5v
| but all P3-866 socket 370 take 1.7v.
| My guess is your 250 only supplies 5.5v on the +12v line which supplies
| power to hd, mb, psu and fans. So that 0.2v difference doesn't boot the pc.
| I researched that stuff when I noticed the psu powering a Cel 333 was only
| 200w yet the psu powered cd,dvd, pci nic, 1-3 hds, usb scanner, onboard agp
| and sound.
|
| http://processorfinder.intel.com/scripts/list.asp?ProcFam=25&CorSpd=ALL&SysB
usSpd=ALL&PkgType=ALL

I was hoping you might have pinpointed the problem, but it looks as if the ? is
still there. The 1GHz CPU (actually 1.13GHz I now find out) is firmly planted
in a motherboard under Arctic Silver, heatsink and fan, so I didn't want to dig
it out to check the specific model. But SiSoft Sandra reports its core voltage
at 1.75. So that's evidently not the answer.

I'm beginning to suspect that I may just have a slightly faulty 866 Pentium. A
friend was using it before he got me to build him a P4 2.4GHz system. He had
been having occasional problems even with a 300W PSU. I was never able to find
a definite cause, but I suppose it could have been the CPU.

Thanks for your help anyway.

Larc



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Click to expand...

I've mistreated a few cpus and haven't found one to fail yet.

I checked the table above again and the same applies to 1.13G, some are 1.5v
models. Check Sandra, download the Wcpuidto or Intel's cpu id to confirm
your cpu id, steppings, etc. Ditto for the 866. Then check the table for
the required voltages.

Sandra might be reporting the voltage range for the cpu line not the actual
voltage though it makes sense that if the mb supplies 1.75v it should power
the 866.

How much voltage is supplied on the +12 by the 250w?
How much +12 voltages does Sandra say you are using?
How much +12 voltage is required by your mb?
Can you post with only mb, memory, video and 866 connected?
 
|
| I checked the table above again and the same applies to 1.13G, some are 1.5v
| models. Check Sandra, download the Wcpuidto or Intel's cpu id to confirm
| your cpu id, steppings, etc. Ditto for the 866. Then check the table for
| the required voltages.
|
| Sandra might be reporting the voltage range for the cpu line not the actual
| voltage though it makes sense that if the mb supplies 1.75v it should power
| the 866.
|
| How much voltage is supplied on the +12 by the 250w?
| How much +12 voltages does Sandra say you are using?
| How much +12 voltage is required by your mb?
| Can you post with only mb, memory, video and 866 connected?

I checked most of the items you mentioned, but still no joy. The 866 CPU does
require 1.65V. I did finally manage to get the 866 to boot, but everything is
slow as molasses in January. But I may have found a problem with the
motherboard mounting that could be shorting out some of the connections. I'm
following up on that as time permits.

Thanks again.

Larc



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