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does the the cpu affect the voltage drop from idle to load?

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Old 08-10-04, 08:00 PM Thread Starter   #1
veryhumid



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does the the cpu affect the voltage drop from idle to load?


I asked batboy this earlier, but I am just curious to know if anyone has an explanation. Is the motherboard and power supply the only things that maintain cpu voltage and voltage drop (droop) from idle to load? I find my system has a pretty big drop, I was wondering if it may be my chip. Is it possible some chips would have higher voltage drops than others? Thanks for the input.

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Old 08-10-04, 11:52 PM   #2
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Hmmm... I'm a little curious about this as well.

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Old 08-11-04, 05:17 AM   #3
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I'd give a qualified yes to that. I say qualified because I'm basing this solely on my limited observations. Under full load I was getting .04-.06v droop with my 2.8c, whereas my 3.2E D0 usually droops .06-.08, with a very rare and very brief .1v droop. This is with a PCP&C 510 psu and a fully sinked and wc'd MAX3.
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Old 08-11-04, 06:27 AM   #4
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The power consumtion of the chips will affect the amount of the droop, but only as a % -- if you have no droop, it wont for any chip.

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Old 08-11-04, 08:36 PM Thread Starter   #5
veryhumid



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Quote:
Originally Posted by Styyn
I'd give a qualified yes to that. I say qualified because I'm basing this solely on my limited observations. Under full load I was getting .04-.06v droop with my 2.8c, whereas my 3.2E D0 usually droops .06-.08, with a very rare and very brief .1v droop. This is with a PCP&C 510 psu and a fully sinked and wc'd MAX3.
yeah i have like a .09 droop when set to certain voltages, .05 for some. what are the rails looking like on your psu when at full load?


thanks for the input everyone!

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Old 08-12-04, 12:40 AM   #6
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The voltage differential between idle and load is proportional to the current that the CPU draws. The voltage drop on a 2.8C will be less than with a 3.2E because the E chip (a Prescott) draws much more current than a Northwood.

On a side note, the voltage drop is normal; in fact it's part of the operating spec. If a motherboard provides a consistent voltage from idle to load, that's not necessarily a good thing; it can be detrimental to the long-term life of a chip.
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Old 08-12-04, 08:23 AM   #7
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Come to think of it, I have noticed a greater amount of undervolting with a Prescott compared to a Northwood, so I think Nookie is right about some CPUs pull more power. The thing is, his IC7 Max3 is dropping from like 1.55v idle to maybe 1.5v load (this is with a 1.575v BIOS setting). This is with a Northwood CPU. I've never seen an Abit mobo drop that much before.

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Old 08-12-04, 09:20 AM Thread Starter   #8
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yeah i am going to kind of rebuild my computer. Put in the old true 430W and try an IC7-G. I'm really asking this because I wonder if my chip maybe damaged.

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Old 08-13-04, 03:41 PM   #9
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Sorry about the late response. Anyway, as displayed by MBM5, my 12v rail idles at 12.04 and droops to 11.92 under full load. I realize MBM isn't terribly accurate when it comes to voltage readings, so if anyone could tell me the best way and locations for voltimeter readings I can give some more accurate results
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