A7N8X High Vcore Shutoff fix

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10-17-2003, 11:15 AM
YoupY

A7N8X High Vcore Shutoff fix

I'm having my third A7N8X now and with all three I'm having the same problem, I can't raise the Vcore as much as I would like. I have tested this with three different procs, but every time I come in the neighbourhood of the 2.1V my system shuts down.

So I started thinking when I saw the Epox mod. This one inspired me to go looking for a datasheet of the voltage regulating chip near the cpu.

Studying the datasheet I saw that there is an overcurrent protection that prevents the the Vcore from getting over 2.1V and that the maximum that the chip can deliver is 2.25V.

Quote:

OVERCURRENT PROTECTION REALIZED USING THE LOWER MOSFET’S RdsON OR A SENSE RESISTOR

So I know this protection is real

Quote:

Output Voltage Protection and Power Good
The output voltage is monitored by pin VSEN. If it is not within +12/-10% (typ.) of the programmed value, the powergood output is forced low. Power good is an open drain output and it is enabled only after the soft start is finished (2048 clock cycles after start-up).
The device provides over voltage protection; when the voltage sensed by the VSEN pin reaches 2.1V (typ.), the controller permanently switches on both the low-side mosfets and switches off both the high-side mosfets in order to protect the CPU. The OSC/INH/FAULT pin is driven high (5V) and power supply (Vcc) turn off and on is required to restart operations. The over Voltage percentage is set by the ratio between the OVP threshold (set at 2.1V) and the reference programmed by VID.

and is giving me some trouble.

http://members.home.nl/youpy/vcore.jpg

I have talked this over with some other tweakers and were pretty sure that pin 10 causes the computer not to boot at voltages higher than 2.1V. The solution seems simple, just cut the pin and see what happens. As fas as we think 2 things can happen:

The mod works and the overcurrent protection is disabled or the mod doesn't work and automatic shutdown will occur even at voltages of 0.1V or higher.

What do you guys think that will happen when cutting pin 10. Or are there some other idea's / theories over how to get a higher Vcore on this board.
10-18-2003, 01:08 PM
YoupY

^^^^^^
10-22-2003, 06:09 PM
kokoro_kara

Any Luck out there??? I wish I could help but this is way behond me. I wish someone would answer. :(
10-23-2003, 08:48 AM
YoupY

I still haven't had time to test the mod. Since this board was going dead on me I have installed another mobo, but I will test this soon. Probaly sometime this weekend or next.
10-29-2003, 03:06 AM
Bra!nFreeZe^

Hey nice info there! :toast: ill try the mod when i get home today,im currenctly at work :)

ill post the results tonight !
10-29-2003, 09:57 AM
YoupY

I'm not sure if all this info is right. I'm nog an elektro guy, but when I saw the datasheet it was pretty sure to me there is a way to disable this protection.

When cutting pin 10 doesn't help pin 13 is also an option. This should disabble the proctection for high amps. If the mod doesn't work soldering the connections back together should revive the mobo again if the chip survives.

Until now I didn't find the time to try this mod myself, but I intend to do this mod somewhere in the future.
10-29-2003, 11:11 AM
xDUCK

Good work! Looks like an open and shut case, IMHO. As you said, just cut the leg. If the board freaks, you can always solder back the connection. :toast:

After cutting the leg, you might want to run the board without the CPU in. Just power it up and measure vcore (with a multimeter). Just a precaution, so you don't fry your CPU. ;)
10-30-2003, 06:36 AM
bias_hjorth

where do you measure the vcore with a multimeter on the A7n8x?
10-30-2003, 07:09 AM
Bra!nFreeZe^

Thats what i would like to know!
10-30-2003, 08:35 AM
xDUCK

Quote:

Originally posted by Bra!nFreeZe^
Thats what i would like to know!

If nowhere else, the caps on the back of the socket should have a VERY accurate reading of vcore (mind you, it's a little inconvenient - I would recommend soldering a little extension line to it so you don't have to flip the board to read vcore :eek: ). :)
10-30-2003, 09:20 AM
Bra!nFreeZe^

hehe thx for the info,but would you mind taking a pic of the place where u monitor the vcore?
10-30-2003, 11:57 AM
YoupY

Vcore can also be measured on the mosfets. I'm not sure which one it was, but is is one in the bottom row. I thought it was on the left legs was for Vcore
10-30-2003, 12:45 PM
xDUCK

Quote:

Originally posted by Bra!nFreeZe^
hehe thx for the info,but would you mind taking a pic of the place where u monitor the vcore?

I have an NF7-S (although I've had 2 A7N8X's in the past)... But any of the caps on the back of the socket will give you a vcore measurement. ;)
10-30-2003, 01:34 PM
Bra!nFreeZe^

hehe okay thx! :)
11-05-2003, 01:05 PM
YoupY

Bra!nFreeZe^ have you tried the mod.

Since I'm currently working 6 days a week I have not found the time to test the board, because I only have one system. I'm currious if you could tell me if it works
11-05-2003, 02:38 PM
Bra!nFreeZe^

Ill do it this week,the reason i havent done the mod yet is because i wont go above 1.85 on the vcore with my currenct aircooling but this week i will get my peltier cooling up and running,and then ill try out the mod :)
11-07-2003, 07:41 PM
kokoro_kara

Quote:

Originally posted by Bra!nFreeZe^
Ill do it this week,the reason i havent done the mod yet is because i wont go above 1.85 on the vcore with my currenct aircooling but this week i will get my peltier cooling up and running,and then ill try out the mod :)

:banana: :banana: :banana: :banana: :banana: :banana: :) :) :wave: :wave: :rocker: :rocker: :YIPPIE: :YIPPIE: :ROTF: :bounces: :bounce: :bounce: :bounce: :wave: :toast: :banana: :comp10: :usa: :banana4: :banana4: :eleph: :eleph: :worship: :up: :up:
11-08-2003, 05:10 AM
Holst

Hi all,

I took a look at this weeks aggo when I was thinking about buyin an A7n8X, but as I got an NF7 instead I never tried it.

When I look at the PDF its pins 13 and 16 that stand out.

They are the cirrent sense pins that controll the overcurent protection, as this is a 2 channel controller each channel is sensed seperately.

Cutting pin 10 and connecting the pin to Vcore out may also work, but you need to be carefull what you attach to. Idealy you need to get onto the Vcore plane once its combined... IE AFTER the output caps, as I dont have a board I cant tell you exactly where but it will be very close to the socket. Pin10 also affects other things.. .so he result of such a mod is a bit unknown.

When the overcurrent is activated the vreg will not shut down as in other designs but will enter "quasi constant current operation" basically it will drop the Vcore by skipping cycles untill the current drops below the threshold... this I imagine would cause very poor stability... is this what you guys experience?

If we look at figure 4 inthe PDF we can see a brief diagram of how the overcurrent operates, basically its all set by one resistor between the ISEN and PGNDS pins...

If you look on your boards between pins 15 and 16 and pins 13 and 14 you should see a resistor thats the same size on both sides... this is the resistor "Rg" by altering its size we can change the OCP setting.

If we look at the equasion for "the current information produced internally"

This is Iinfox = (Rsense Rphase) / Rg

So we want the reported current Iinfox to appear to be less than it is... as Rg is on the bottom of the equasion we make Rg larger to make IinfoX smaller.

I "think" this relationship will be linear, add 50% to Rg and add 50% to the overcurrent.

So the mod is simple find the two resistors between pins 15-16 ans 13-14 and increase there size by 50% or so.
You may be able to remove them all together, although id prefer to keep them intact.

Using a pair of fixed size resistors (on sort wires if space is cramped) would be the best.
11-08-2003, 05:55 AM
Bra!nFreeZe^

Quote:

You may be able to remove them all together

isnt that alot easier than just adding new resistors ?
11-09-2003, 12:11 PM
Holst

If it works yes, but im not sure if it will, that seemed a bit too easy to me...
11-09-2003, 02:04 PM
Bra!nFreeZe^

hmmm i think i will try just to cut the measurement pin first, and if that doesnt work then i will try your suggestion
11-09-2003, 02:28 PM
Holst

Cutting pin 10 almost certainly wont work.

You will have to solder it to the Vcore output.
11-09-2003, 02:30 PM
YoupY

I think the measurement pin is still the best option to try first, because "the problem" only occurs while pushing Vcore over the 2.1V. When doing this in de bios it will result in an no startup. When I do this in Windows with a VR Windows will freeze.

Because of this I think it has more to do with the Volts that the chips has to produce than with the amps that is uses.

But If cutting Pin 10 doesn't work then modding Pin 13 - 14, 15 - 16 is also a good option. Maybe it is possible going over the 2.1V when both mods are done.

I still want to try this, but time is a §§§§§. I have way to much work to do lately :( :( :( and since I have only 1 sys which is all build in, it isn't easy for me to test this in a few minutes and than build in my wc setup, prommy etc. in an hour or less sometimes
11-09-2003, 02:34 PM
Bra!nFreeZe^

Quote:

to test this in a few minutes and than build in my wc setup, prommy etc. in an hour or less sometimes

Of curse not i will test this tuesday or wednesday because im going to finish my pelt setup there
11-09-2003, 11:44 PM
sysfailur

So no firm solution yet eh? Damn :( It would be rather nice to get some higher volts.
11-10-2003, 06:19 AM
Bra!nFreeZe^

hey sys i expect that u will do a few experiments to find a solution to this problem! ;)
11-11-2003, 08:53 AM
Holst

I dont have the board to play with,

Good luck with your testing Brainfreeze, ill be interested in how it goes.
11-11-2003, 02:00 PM
Bra!nFreeZe^

Quote:

ill be interested in how it goes

Hehe i sure am too ! ;)

but thx for the info and the support!
11-12-2003, 09:00 AM
Dieter@be

Brainfreeze, did you try it by now?
11-12-2003, 11:59 AM
Bra!nFreeZe^

not yet im having some problems with my tec psu which i expect to fix by tomorrow!
12-25-2003, 11:20 AM
Electroid

Mod needed, help...
12-25-2003, 11:38 AM
PMM

I know nowt :D ;)

\/ PM me if you want to know more I have put 2.35 into my Barton.
12-25-2003, 01:33 PM
Electroid

Why can't write some helping-quide to this topic? Pics are also welcome.
12-25-2003, 02:17 PM
PMM

Its given me a edge on the competition ;) so I've limited who or
who does not have access to it.

I'm the only who knows how ;)

I'm sure Sys will vouch for my knowledge of the Asus Board ;)

My Claim to fame is here......
http://www.xtremesystems.org/forums/...&threadid=8274
12-25-2003, 02:53 PM
Electroid

:stick:
12-25-2003, 03:26 PM
Holst

Quote:

Originally posted by PMM
Its given me a edge on the competition ;) so I've limited who or
who does not have access to it.

I'm the only who knows how ;)

I'm sure Sys will vouch for my knowledge of the Asus Board ;)

My Claim to fame is here......
http://www.xtremesystems.org/forums/...&threadid=8274

I dont mind people keeping there tweaks to themselves but to brag about having a mod and not telling anybody seems a little calous to me.. especially when these guys may kill there systems testing the mods I have worked out (without my own board to test on)

If my mod is wrong can you please PM me and explain why? I dont want anybody to cause any damage for no reason.

Persoanlly im here to help and share knoledge, not just for bragging rights.
12-25-2003, 04:57 PM
PMM

That's my main reason for not wanting to put up the mod.

It is also not to say what you are doing is incorrect!! my method
is rather different than just directly doing something to the
controlling IC.

Quote:

I dont mind people keeping there tweaks to themselves but to brag about having a mod and not telling anybody seems a little calous to me..

erm hello i'm not keeping to myself (See above) I have indicated
I know how to get above the std Vcore and I have said if you
want details to PM me that is not keeping it to myself is it?

I have been carring the indication in my sig since doing way back
when ;) ..... and I have given the details to someone else but
on the basis it not put up on the forums.

If your modding the chip you know the score its at your risk, the
fact its put up here is more damaging since you do not know
as such if it works.... people are going to see this and based
on the given info try and do it are they not?

I would never put up such a thread without knowing what I was
doing was correct.

This mod I'm not going to put up end of story - but It works.
Its a Solder Job & a SMD resistor has to be removed off the
motherboard for it to work and its one near the CPU socket.
it involves 3 wire mounting points and could be an issue for
people using phasechange system due to wire mounting points.
12-26-2003, 03:21 AM
Electroid

PM sended to PMM (my first).
12-26-2003, 01:03 PM
YoupY

Nice work.

I can understand you have your reasons for nog sharing this mod, but since I started this thread I'd really like to know the details.

PM sended :) and hoping for a swift answer, since I'm really curious how you did it.
02-09-2004, 12:34 PM
YoupY

ok, here it is:

I've tried this the way PMM sent to me and he agreed I can post the way to do it here.

I've tried out the mod with an el cheapo aircooler, and because of that I wasn't able to squeeze more then 2.2V out of it, since temperatures were in the neighbourhood of the 100 degrees. (I know, bad temps due to not enough thermalpaste) But with some decent cooling it shouldn't be a problem.

first the pics:

http://members.home.nl/youpy/vcore_fix.jpg

the arrow should be pointing to the other resistor that has to get of the board

http://members.home.nl/youpy/vcore_mod.jpg

needed to perform this mod:
- 5k VR
- 21 ohms 1/4W resistor

The 5k VR can should be at the default setting, so you'll read 2,5K on each pin. How you'll have to turn it depends on how the wires are put to the VR. It isn't a very clean method, but the core voltage doen't raise much, so probally a VR with less ohms will do as well.

quote from PMM:

Quote:

The Mod as such does the job of overiding the Overcurrent but
also acts as a volt mod in its own right.

So if you have any current Vcore Mod its not strictly needed
when this one is done.

The 5K varible - its a bit bizzare no real value as such
the effect loops around but if you make your resistance
minimum on the side of the variable that connects to the
stand alone resistor you can't go wrong just work it up
until desired results my pot is at 50Ohms +21ohm for the
but as said the varible can be anything s the effect loops
throughout the resistance range.

There maybe a possibility you may here a buzzing sound
when gone to far (too high in voltage) this seems normal
not sure what causes it but nothings ever blown

2.3v is the normal max before tripping but I've had it upto
2.35v according to motherboard monitor while adjusting with
windows running.

First put the 21 ohm resistor on one of the legs of the VR and solder that on to the spot in the pic that is marked as (1). Do not solder it directly to pin 6 but use the cap that is there.

The next step is removing the resistor from the board that normally is in spot marked with (3).

after that you'll have to solder a wire from point (3) to the center leg of the VR, and a wire from point (2) to the other outer leg.

That's it. Which way you'll increase the core voltage depends on where the outer legs connect to.

I think this mod could give some problems for prometeia users, since the place to solder normally is covered with sealstring and the black thingy.

Good luck with this mod and don't kill your board with it. I won't be responsible for any damage you can do to it.
02-10-2004, 07:40 AM
NoStra

I have done the mod as you have described YoupY and have removed my old Vcoremod. But now I get the max voltage of the bios. Doen't matter If I give it 0 ohm... Can someone help me, maybe I have overlooked something.
02-10-2004, 11:40 AM
YoupY

I've helped Nostra out and he is doing 2.2V atm.

please notice all legs of the VR are used in this mod.
02-12-2004, 08:32 AM
Electroid

Quote:

Originally posted by YoupY
I've helped Nostra out and he is doing 2.2V atm.

please notice all legs of the VR are used in this mod.

:( my vcore mod is still only up to 2.08V.

I tryed that different mod with no effect at all? Vcore doesn't rise.
02-12-2004, 09:04 AM
NoStra

This is how the mod has to be....

http://www.fewture.cistron.nl/vcore_mod.jpg
02-12-2004, 11:33 AM
Electroid

Ok. Just like I did it, but only with 5k VR.
Maybe I'll have to try it again...

OMG my mobo is in those pics :p.
02-12-2004, 11:48 AM
NoStra

Quote:

Originally posted by Electroid
Ok. Just like I did it, but only with 5k VR.
Maybe I'll have to try it again...

OMG my mobo is in those pics :p.

I just checked your membench @ 260Mhz...but you run it at 2.0 2-2-5 timings. Why not on 2.0 2-2-11? I got 3945mb/s at only 254mhz fsb... I think you will gain some mb/s if you change your timings!
02-12-2004, 03:58 PM
YoupY

Quote:

Originally posted by Electroid
Ok. Just like I did it, but only with 5k VR.
Maybe I'll have to try it again...

OMG my mobo is in those pics :p.

it doen't matter much if you use a 5k or 2k vr. I'm thinking 5K may be a bit to high, since I could turn the screw quite a bit before I noticed an increase in the Vcore, but a 5k will work.

I don't know exactly anymore if you have to minimize the resistance going to point 1 or point 2 to get a higher Vcore, since it's quite a while ago I tried this mod out. board is in a closet now, since I'm running A64. Can you help us out here Nostra??

If you know which point has to be set to high resistance for getting the original voltage you can also use a 2K. I only used the 5K in the guide since PMM described it that way and I wasn't sure which way you'd have to turn increasing the Vcore and I don't want anybody to kill there board by a faulty descirbtion.

if you can't get the mod to work please PM me and I'm happy to help you out.
02-13-2004, 05:47 AM
NoStra

When you decrease the resistance to 2...the voltage will UP. If the mod doesn't work. Then you have done something wrong. The first time I did the mod, I also did it wrong. Now it works for me. 2.3V without a problem :D
02-13-2004, 12:33 PM
Electroid

Quote:

Originally posted by NoStra
When you decrease the resistance...the voltage will UP

Decrease between 1&3 or 2&3?
02-13-2004, 01:43 PM
YoupY

You'll have to decrease the resistance going to point 2 in the picture to get a higher Vcore.
02-14-2004, 03:26 PM
PMM

I do not know if you lot are seeing the same effect I get,
i mention that the effect loops around (well does on mine :D)

my best way of explaining (values given for explination purpsoses only are not reflect of reality)

vr @ 50ohm = 2.3v
vr @ 500ohm = 2.1v
vr @ 1000ohm = 1.8v
vr @ 2000ohm = 2.2v
vr @ 3000ohm = 1.8v
vr @ 4000ohm = 2.25v

hope that makes sense?

But it seems min resistance towards point 2 yeilds best results about 70ohms mark.

I cannot test anymore as both my boards are demodded in prep
for some new A64 gear once I pull the trigger on the CC :comp10:
so I can't put any values to the effects seen on mine.
02-14-2004, 03:37 PM
YoupY

I didn't notice this effect.

I've increased the resistance to one side and that gave me an increase. After that I turned the pot the other wat, but not all the way.

thanx for clearing this up. This shines a new light on the mod and it's getting clearer to me how it works.

Thanx m8 :toast: