vdrop and voltage spikes?

[Buttnose]

I bought a 2B pencil to correct the idle vdrop of 0.046 on my Asus Commando. However I'm having second thoughts after having read (but not really understood) an article about vdrop.

Theres quite alot of information to digest and I'm looking for someone to tell me whats what, and hopefully whats best.

The CPU VID setting establishes the absolute maximum allowable processor supply voltage experienced during transient conditions and is not the target idle voltage.

Together, Vdroop and Voffset ensure that the peak CPU supply voltage seen during heavy to light loading changes remains well below the established maximum. If you determine that 1.17V, as in the case above, is not sufficient for maintaining CPU stability under load, simply increasing the CPU VID does correct the problem.

This conflicts with my caveman way of thinking of vid, I've always thought of vid as a unchangable factory preset minimum operation voltage for the processor at stock speed.

If you're asking yourself what's the problem with this, consider the case of a CPU VID of 1.60000V - because the user feels this is the absolute maximum CPU voltage that they will allow. Just how high do you think CPU voltage will go after leaving a heavy load condition? We can't be sure without knowing more of the details, but we can certainly conclude that it will be well in excess of 1.6V.

Again they seem to me to be talking about vcore when they say vid. Does anybody have measurements for these voltage spikes?

Finally, let's take one last real-world look at the consequences of removing Vdroop. ASUS' implementation of this feature, labeled as Load Line Calibration and included with their latest line of motherboards, is particularly worthy of our attention for a number of reasons. The first is that setting lower voltages with this option enabled actually results in a condition in which the CPU voltage under load is higher than the idle voltage. Imagine our confusion as we desperately struggle to understand why our system is Prime95 stable for days yet continues to crash under absolutely no load.

Is this relevant to pencil modding?

I'm really out of my depth here now, but isn't the whole thing a result of VRMs not being able to readjust voltage to the processor fast enough to avoid voltage drops? Couldn't it be made so that the voltage supplied is distributed through more VRMs (which are all active regardless of actual voltage in use), each of which acts only for certain voltages and are switched to when their voltage control range is reached. For example VRM #1 controls 1v-1.03v, VRM #2 controls 1.031v-1.05v. Would this not eliminate, or decrease "overshoot"?

I get the feeling that I'm confusing a number of things for one another and totally imagining other things.

serious looking graphs-
http://www.anandtech.com/cpuchipsets/intel/showdoc.aspx?i=3184&p=5
http://www.linear.com.cn/pc/downloadDocument.do?navId=H0,C1,C1003,C1042,C1143,C1083,P1735,D4438
http://www.anandtech.com/cpuchipsets/intel/showdoc.aspx?i=3184&p=6

semi-related forum posts-
http://forums.anandtech.com/messageview.aspx?catid=29&threadid=2055486&highlight_key=y
http://www.ocforums.com/showthread.php?t=537930
http://www.overclock.net/intel-motherboards/314922-correct-vdrop-vdroop.html

 

[sirmonkey1985]

some boards allow you just to change the cpu vid.. for example my board you can change between 4 different cpu vids.. the auto setting just goes off the cpu voltage including vdroop.. which on my processor is 1.17v after vdroop even though its set to 1.2v if i change the cpu vid i can choose between .800 .850 .875 .880.. by changing that.. it changes the final voltage after vdroop to 1.800 1.850 1.875 1.880 which is suppose to help stability.. basicly its a fake vdroop offset option to fine tune an already limited voltage option on this board since unlike intel this board only allows me to do +.10 +.20 +.30 +.40 voltage changes..

but thats my guess what their talking about with the first part about changing the cpu vid..

the pencil mod may help.. but check on your board if you have the voltage offset or load line calibration option.. ive actually seen on some boards where with it on the vdroop is exaggerated compared to when its off.. because a .046v vdroop isnt all that bad.. my board has a .024 vdroop.. and my m2n-sli board is even worse.. i think it has a .039v vdroop..

if anyone thinks im wrong on 1 or more parts feel free to correct me cuz i sure as heck am not an intel person so i dont know everything on intel boards..