Starting to vmod - desperately in need of help

[GGuyZ]

I'm willing to perform a vcore/vdroop mod on my board.The vdroop is crazy(setting 1.6v in bios actually gives 1.4v-1.52v).

I've read the stickies(and the comprehensive guide on this forum too), and I'm doing the best I can to get things moving.
It seems that the guide on this site is a bit too technical for me, but I am willing to learn(I'm also a pretty quick learner).

I guess I'm better off with asking specific questions. So here's my first one:
I tried looking for the voltage controller chip. I found a few chips but none of them seem to have a datasheet on google.
These are the chips I found:
a. K3918 - there are actually 6 of those. 4 in a row, and the other two or found separately.
b. ISL8566, H548QG(two lines. no results on either in google).
c. 331OGH, 549298(two lines. no results on either in google).
What am I doing wrong? Is one of these the right chip? or none of those? I can upload pics if you guys need them.

I would truly appreciate your help. Everybody's gotta start somewhere, so I'm sorry if this sounds a little newbish to you. I am willing to learn and succeed!

[Super Nade]

Hello and Welcome to the forums! You are looking for a buck regulator. Typically it is a 16 pin SMT chip as apart from the DC-DC conversion, it also has contol circuitry in it. A few pics would help. :)

Usually, these chips are fairly close to the phase inductors and DRAM.

[GGuyZ]

Thank you for your reply and warm welcoming!

Here are a few pics to describe what I was able to find:

The first two pics are near the DIMMs. you can see the chips that might be what we're looking for:

Picture 1 - the chip you see here is the one I checked. Nothing came up in google
http://img117.imageshack.us/img117/9368/rightcpu2ft5.jpg

More chips near the dimms. However, they seem kinda far from the CPU socket, aren't they? Could only read half of the label because the number isn't clear at all. Google didn't come up with anything either.
http://img177.imageshack.us/img177/3381/cimg0322gb1.jpg

This is a picture from the other side of the CPU socket. Right under the PSU. You can see the K3918 chips I saw. I believe these are mosfets and not the voltage controller chip?
http://img470.imageshack.us/img470/6421/leftcpu3zm7.jpg

[four4875]

yeah those are mosfets. maybe get a shot of the area in the last pic, but back some so we can ee more of the surrounding area?

[GGuyZ]

Thank you again :). I appreciate the help! Finally I feel we are getting somewhere!

Here's a picture of the surrounding area, as you requested:
http://img180.imageshack.us/img180/9894/cimg0325kp6.jpg

The following 4 pics construct the above picture, only magnified. the third picture is actually the one from my previous reply:

http://img127.imageshack.us/img127/4497/leftcpu1zs8.jpg

2:
http://img129.imageshack.us/img129/7117/leftcpu2uk2.jpg

3:
http://img470.imageshack.us/img470/6421/leftcpu3zm7.jpg

4:
http://img470.imageshack.us/img470/8022/leftcpu4lt3.jpg


If these are mosfets, how will they help me since I really need the voltage regulator chip, don't I?

[Super Nade]

Thank you again :). I appreciate the help! Finally I feel we are getting somewhere!

Here's a picture of the surrounding area, as you requested:
http://img180.imageshack.us/img180/9894/cimg0325kp6.jpg


The above 4 chips are linear voltage regulators an the SMT ones are probably quad-signal OpAmps. I'm not sure if the VR's are programmable or not. You need a programmable regulator to swing the voltage, if not you will merely stress the linear regulator.




The following 4 pics construct the above picture, only magnified. the third picture is actually the one from my previous reply:

http://img127.imageshack.us/img127/4497/leftcpu1zs8.jpg

The above chip seems to be a Quad OpAmp or a small signal Amplifier as well. You should be looking for the buck-regulator, which is usually > 8 pin.





2:
http://img129.imageshack.us/img129/7117/leftcpu2uk2.jpg

Voltage regulators again.



3:
http://img470.imageshack.us/img470/6421/leftcpu3zm7.jpg

VR's. K391's, hmm.. I have not heard of this before.


4:
http://img470.imageshack.us/img470/8022/leftcpu4lt3.jpg


If these are mosfets, how will they help me since I really need the voltage regulator chip, don't I?

[Super Nade]

http://img177.imageshack.us/img177/3381/cimg0322gb1.jpg

The 16 pin chip could be what you are looking for.

[GGuyZ]

Thank you!

Please accuse me if some of my questions will sound 'newbish' to you. Like I said, I'm a pretty experienced overclocker. But with electricity I am indeed a newbie, but willing to learn.

Therefore, I'm unfamiliar with some of the acronyms you used. But let me see if I understand you correctly - basically those Voltage Regulators aren't of much use to me in the modding part. Can I use those to measure the vcore with a multimeter? If so how can I do that? I'm a bit worried of shorting things up.

And the more important question I have- that chip on the last image(to the far right) has only got 14 pins, not 16 like you said. Does it matter? How can I check more on it, since reading the label is impossible - it appears to only be faintly visible.

[four4875]

i think he quickly glanced at it and didnt count the pins, didnt notice it was a 14 pin and not a 16. i also noticed that he said 16 when its a 14.

in reading the chip, it sometimes helps to try looking at it from different angles, and shine light on it at different angles.

[GGuyZ]

Hi again.

I tried using different angles. didn't really help. I'll try in a few hours (in full day light.. it's 1am here now) - it might be easier then.

But if this is a 14pin chip - is it really the one I need? or does that disqualify it from being the voltage controller chip?

[Super Nade]

As four mentioned, I just glanced over and miscounted. :)

Without the datasheet it is not easy to mod a chip. If I know for sure that it is indeed the chip to be modded, there are ways to see where on the chip the mod needs to be done.
As for those series of voltage regulators, there is no lable on it either. So, I'm not sure if they are programmable or not. If they are just linear non-programmable VRegs, there is no clean way of modding them as you would have to add a load across it and there may be a few problems if the case is ground (not very sure about this though).

The ISL chip is made by Intersil and I'm pretty sure it is a PWM controller (we are on the right track), but I'm unable to find a datasheet for that. I searched for chips with all your numbers by prefixing them with AN (Analog), LM (Linear technologies), MX (Maxim Semiconductor and on ON-semiconductor's website. No luck. :(

[GGuyZ]

Wow Super Nade! thanks for spending so much effort in helping me. I truly appreciate it!

I will do my best to find the number on top of that 14pin chip. Hopefully this will give us a better lead!

about the label on the VR - it's K3918. the most related datasheet for this one is this: http://www.alldatasheet.com/datasheet-pdf/pdf/113052/NEC/2SK3918.html
But I seriously doubt it's the same thing. This is for a transistor I believe, and we're dealing with a VR.

I wasn't able to find anything for the ISL chip either. But could you please explain what a PWM controller is?

Will be back later after attempting to locate the number on the 14pin chip!

Thanks again!
Guy.

[Super Nade]

Wow Super Nade! thanks for spending so much effort in helping me. I truly appreciate it!

I will do my best to find the number on top of that 14pin chip. Hopefully this will give us a better lead!

about the label on the VR - it's K3918. the most related datasheet for this one is this: http://www.alldatasheet.com/datasheet-pdf/pdf/113052/NEC/2SK3918.html
But I seriously doubt it's the same thing. This is for a transistor I believe, and we're dealing with a VR.

Exactly. Nobody really uses discrete transistors these days. Plus, most power transistors come in an SOT223 package.


I wasn't able to find anything for the ISL chip either. But could you please explain what a PWM controller is?

Will be back later after attempting to locate the number on the 14pin chip!

Thanks again!
Guy.

PWM=Pulse width modulator. I'll post up an article in this forum tomorrow evening where you can read all about it. ;)
If you

[four4875]

in short, the regulator works by turning power on and off really quickly, and through caps and inductors it averages out the voltage between the on and off states, and the PWM controls how long it is off and on, thus controlling the voltage.

[Skeith]

You might need to take your heatsink off your CPU in order to get it in the pic. It should be near the mosfets for the Vcore and the large filter caps.
The ram typicaly has its own controller.

Basicaly what you need to do is find the PWM. The pulse width modulator is a chip that pulse width modulates a voltage.
--------------------------------------------------------------------------
What is it your looking for and how does it work?

Modulation is a way of manipulating or encoding a signal for a certain use. FM and AM (Frequancy modulation and amplitude modulation) are modulation types for transmitting radio signals.

Pulse width modulation is simply a type of modulation that varied the pulse widths of a voltage

It controlls how long the voltage is off and how long it is on. This is called the duty cycle. for example A duty cycle of 50% would be the off state and on state being exactly the same length.

The mosfets are high current switches controlled by the PWM signal. They witch large ammounts of power into the filter consisting of capacitors and inductors.

Capacitors are simply devices that store charge and have the capability to release it at a high current ratings.

Inductors are devices that resist change in current and voltage. A change in current will result in a change in voltage. etc (Its hard to explain if you dont know the theory of inductance and reactance but that is not needed here)

Together the capacitors and inductors filter, average out and smooth the switched voltage from the mosfets by the PWM creating the Vcore.

The PWM has a buck converter in it. It is a device that will accept a feedback of the output voltage. Depending on the voltage level being returned it will change the duty cycle wich in turn will change the voltage ouput by the filters thus regulating the voltage.

All of these together is what is know as a switching regulator. A voltage regulator that regulates by rapidly switching into a filter.
--------------------------------------------------------------------------
Why does a computers volatage fluctuate under load?

It is all determined by the capacity of the capacitors. The higher capacity the more charge they can store. Because all circuits have resistance there is what is known as an R/C time constant Resistance/Capacitance time constant wich is the relation of time it takes for a capacitor to discharge being supplied through a certain resistance.

When the CPU loads the regulator it draws current. It draws more current the harder is works. Bassicaly the more current the CPU draws the faster the capacitor discharges. As it discharges the voltage collapses (falls)

To fix the collapsing voltage read by the PWM the duty cycle is changed. This creates a longer on time and shorter off time. The capcitor can then be charged longer per cycle. Now the voltage goes back up.

If the voltage reaches the treshold (or max limit) the duty cycle changes again shortening the on time and lengthening the off time wich then causes the voltage to go back down.

The regulator does this so fast it is hardly noticed untill the CPU draws a large ammount of current known as a spike or surge. This rapidly discharges the capcitors and then the duty cycles are changed. Since the surge is short the voltage drops abruptly and then raised up to the threshold and back down to the normal in a matter of a few miliseconds.

If you were to plot your CPU voltage on a graph you would see that right after the voltage droppes past the normal it raises up. It goes slightly past the normal and then back to the normal . This causes a fluctuation or droop that can cause miscalculations in the CPU causing errors, crashes, or is worst cases corupt data.

The best way to fix this problem would be to add another phase into the regulation (number of filters and switches) the phases are usualy ofset by a certain degree in the duty cycle to create a more even filtering.
Some cheap boards have 2 phases while moderate ones such as my NF7 have 3. Higher end boards have 4 or more, some up to 8. Because of the more filters and switches the voltage is more stable.
However adding a phase is not easy.

The number of phases can commonly accounted for by counting the number of mosfets and inductors (coils near the CPU socket). There are typicaly 2 mosfets and 1 inductor per phase. A 2 phase regulator would have 4 mosfets and 2 inductors. The number of capacitors can vary.

The second best way to fix a droop is to replace the capacitors on each phase with ones of higher capacity. This is also not too easy and often imposible due to limited space.

That is where volt and droop modding come into play.
I will let others more experianced with that section cover that for you.
It involves manipulating the feedback reading into the buck converter.

If you are wondering yes I am planning to be an electronics engineer
and will be starting technical college in the fall.

[GGuyZ]

Super Nade, four4875 and Skeith - thank you for your explanations. I understood most of them, or atleast the general idea. :)

I have to admit that at first I would rather use a more moderate vmod. Either a vdroop or a vcore mod that is made using a pencil/conductive ink(by tweaking the resistors and not soldering anything). This is because I wish to make things reversible as this is my first time vmodding. If this will work and indeed improve my overclocking abilities - I might try more complex methods of soldering(which I have done before, but not in such a small and detailed surface like a motherboard).

And now I may return to the more practical part - I have VERY good news!
I was able to find the labels on the 14pin chip and on the ISL chip(It seems that I've done a mistake before in reading the ISL chip):

the 14 pin:
AZ324M-E1
537BN

I found this datasheet for this chip. I hope it's the right one: http://www.hengsen.cn/bcddata/az324.pdf
It appears to be suitable!

The ISL chip's label:
ISL6566
CRZ
H548QG

Here's the datasheet for the ISL chip:
http://www.intersil.com/data/fn/FN9178.pdf

Finally we have something to work with! Cheers! :) :clap:

Thanks again for all your help guys! Will be looking forward to your answers.
Guy.

P.S: Skeith: Good luck in your studies. I will be starting electronical engineering + Computer Science studies next year myself. I haven't got much experience in the electronics field, but I will learn :).

[Skeith]

P.S: Skeith: Good luck in your studies. I will be starting electronical engineering + Computer Science studies next year myself. I haven't got much experience in the electronics field, but I will learn :).
Glad to see somone else venturing into the feild of electronics. Most of the stuff I know is self taught from the internet and mostly trial and error. LOL
Good luck in your studies.

Back on topic.
The Intersil looks like she be the one were looking for.
ISL6566
The 6566 is the same chip I vmodded on my video card for mem and GPU mods.
Its a buck converter+mosfet driver for AMD applications etc.

[GGuyZ]

Thanks again :).

I'm afraid I'm a bit lost now. I tried reading the guide on this webpage again and comparing it to the datasheets I found. Things are getting a little too technical for an electricity newbie like myself.

I was wondering if you guys can give me a direction to what I should be doing now?

[Super Nade]

Hang in there man, I'll get on this after my midterm exam today. ;)

In the meantime, pm me your gmail id and I'll share an article I've written, with you. It is about the basics of Buck regulators.

[GGuyZ]

Sorry mate! I wasn't aware you had a midterm. Good luck! Hope it went well...

I PMed my gmail to you.

thanks again,
Guy.