How to volt mod IC7 Vmem

[Charles Wirth]

Before you turn off your machine set the default vmem to 2.6v

Locate R50 on the motherboard that sits between the DIMM3 memory slot and the winbond chip. You will see a surface mount resistor and the spot designation of R50 silkscreened into the motherboard.

Now that you have located R50 you need to desolder it and not harm the other components close by. I suggest a very pointy soldering iron and solderwick tapped on each side rather than prying with soldering iron at both sides quickly untill it falls off.

Hopefully you have 2 nice clean pads to use as contact points.

Use a continuity meter and test the back pad for ground (one farthest from winbond chip).

Check the 1K vr and set it to 250 ohms and connect the center pin to the contact pad closest to the winbond chip (doesnt ring as ground with continuity test to ground) and the ground pin you setup vr at 250 ohms to the ground pad or a ground of your choice.

If you did not reset bios before you turned off your machine, reset bios to default while your hands are still in the area.

Fire up and you should be reading 2.67v in bios. This should be a safe voltage for anyone to start out with.

Last note about this volt mod is that it is the opposite of other volt mods. Meaning if you increase the value on the VR (250 Ohm to 300Ohm) it will increase the voltage to the memory.

Thanks JCViggen, Macci, and BMG for notes posted.

I will upload pics.

[bmg]

I've also done the ddr VTT mod to my board to keep it at Vmem/2. Unfortunately it's not as easy as Vmem, requiring a trace on the board to be cut and soldering to pin 7 on the W83303D chip. I tried to take some pictures when I did it, but couldn't get my d*mn camera to focus properly, even with macro mode enabled.

[Charles Wirth]

R50 location



Bad pic of the wires in place.

[ztop]

Originally posted by bmg
I've also done the ddr VTT mod to my board to keep it at Vmem/2. Unfortunately it's not as easy as Vmem, requiring a trace on the board to be cut and soldering to pin 7 on the W83303D chip. I tried to take some pictures when I did it, but couldn't get my d*mn camera to focus properly, even with macro mode enabled.

great job! do you have other immages more clear???
thanks

[Yozza]

How much will one gain from the DRAM VTT mod?

[Manoj]

I was hoping more of a bios mod to increase the VDD voltage.

Anyway can you update more pictures?

Desolder the R50 resistor meaning you have to remove it only? I am not good in this but I am going to be asking someone to do the mod for me.

Can you update some more pictures so that I can show my friend?

[Charles Wirth]

The R50 resistor has to be removed. It is a 0 Ohm and basicly does nothihng unless a higher value is installed.

Currently the IC7 undervolts the memory and there is no BIOS update to increase the value beyond 1.8v (1.76v actual)

If you remove the resistor you MUST install something in its place or just bridge the contact pads with solder.

If the circuit is left open it will cause serious damage to the memory and possibly to the motherboard.

I suggest starting out between 200 and 300 Ohms to be safe.

I will try to get better pictures.

[ztop]

thanks FUGGER...i'm waiting new immages:thumbsup:

[JCviggen]

As a note of warning


Be careful when you unsolder the resistor.

I killed my good friend Jupiler's IC7 doing the Vmod on his board. Worked great on mine, but on his I used his soldering iron which got much hotter. I think that the solder of the pads melted completely which worked them loose a bit. (my soldering iron is less hot and only melts the surface)

Anyway the pads came off and despite my attempts to get some sort of contact point beneith the surface, I was unable to revive the board

So do be careful not to pull off your soldering pads or smth...

[Manoj]

I got my Abit IC7-G modded.

Now this is what I get for memory voltage:

2.5V = 2.7V
2.55.V = 2.75V
2.6V = 2.8V
2.65V = 2.85V
2.7V = 2.9V
2.8V = 3V

This is how I have set my resistor.

I can raise it more so that I can have the 2.8V to read 3.2V but I don't want to take a risk.

Currenly I am running my rams at 2.5V which the hardware monitor shows 2.7V.

I can run my Twinmos rams at DDR 500 at 2.65V which the hardware monitor shows 2.85V.

I am surprised that my Twinmos PC3700 can't run at CL-2 at DDR 500 even when I increase the Voltage. It just runs well at SPD timing.

I just want to ask if the VTT (DDR) not being half of the DDR voltage is a problem or not?

Normally it should be half. If the DDR voltage in the hardware monitor shows 2.85V, the VTT (DDR) is actually at 1.32V. Is this okay?

Are you guys going to do that VTT (DDR) mod or is it fine if it is left alone?

[Yozza]

I shall be trying this mod out on my IC7-G as soon as my 3.0GHz 800FSB P4 arrives.

How much difference would the VTT mod make though? ... as the termination voltage should be half of the DDR voltage.

My board seems to have DDR voltage fairly smack on the BIOS setting though. Winbond HW Doctor is reporting 2.80V (with ocassional jumps to 2.78 and 2.82) when 2.80 is selected in the BIOS. VTT is at 1.38 - 1.40V.

What it is reporting wrongly though, is my CPU temperarature - 63C under load at 3.06GHz P4 with the big stock cooler. The P4G8X I had previously was reporting ~50C under load. Seems a common problem with all ABIT boards, and this IC7 is no exception as many have discovered

[hipro5]

A clearer photo.....

[macci]

bmg or hipro5, did the VTT mod help?

[hipro5]

Originally posted by macci
bmg or hipro5, did the VTT mod help?

No sorry macci....I can't get the datasheets from the company coz they are NOT linked yet......I'm playing on my on to do so......I managed to get 1/2 VTT of my Vmem BUT at a standard Vmem.....If I change from into bios the Vmem then the VTT doesn't change.....I have to find somehow the datasheets to do so.......

[Manoj]

Is the VTT mod really needed?

So far not I have modded the VDD but not the VTT and no problems.

[bmg]

I don't think I've pushed Vmem high enough to where VTT made much of a difference. It makes sense that keeping VTT centered at Vmem/2 would be best, but being a little off doesn't seem to matter much. One thing I did notice is that my Vmem seemed to fluctuate quite a bit when I pushed to to around 3.0V or higher. With VTT centered at Vmem/2 the voltage seems more stable, but that's hard to quantify. If VTT is too low then low to high signal transitions will be slowed slightly. High VTT (not a problem here) would slightly slow the high to low signal transitions.

Here's basically what's involved with the VTT mod. Carefully cut the trace between pin 7 of W83303D and MC50. MC50's pad closest to W83303D pin 7 has a trace connected to it which makes a long trip around the board to the temp/voltage/fan monitoring chip. Next to this MC50 pad is a small via in the board which connects to the VTT voltage. The Vmem approach of just adding resistance between this point and pin 7 (VTT sense, or BT_sen) doesn't work, since the internal resistance to ground of the W83303D pin 7 is too large. Basically I connected small gauge wires to pin 7 and the MC50 pad closest to the W83303D (after cutting the trace connecting them). Mount a 1k pot in a convenient place and connect these wires to it. Solder a fixed resistor (approximately 8k-10k) from pin 7 to ground. I found it convenient to solder it to the pot rather than to pin 7 directly. Increasing the pot's resistance will now increase VTT. Once this pot and the Vmem pot are both set VTT and Vmem will track properly when the voltage is changed in the bios.

This mod will be difficult to do without the proper equipment. Soldering to pin 7 is especially difficult to do without a very fine tipped soldering iron and using magnification. Shorting pin 7 to adjacent pins will probably be disastrous. Obviously cutting the pc trace from pin 7 to MC50 must be done carefully. Standard disclaimers apply.

hipro5, pm or email me your email address and I'll email you the W83303D datasheets.

[Manoj]

Originally posted by bmg
I don't think I've pushed Vmem high enough to where VTT made much of a difference. It makes sense that keeping VTT centered at Vmem/2 would be best, but being a little off doesn't seem to matter much. One thing I did notice is that my Vmem seemed to fluctuate quite a bit when I pushed to to around 3.0V or higher. With VTT centered at Vmem/2 the voltage seems more stable, but that's hard to quantify. If VTT is too low then low to high signal transitions will be slowed slightly. High VTT (not a problem here) would slightly slow the high to low signal transitions.

Here's basically what's involved with the VTT mod. Carefully cut the trace between pin 7 of W83303D and MC50. MC50's pad closest to W83303D pin 7 has a trace connected to it which makes a long trip around the board to the temp/voltage/fan monitoring chip. Next to this MC50 pad is a small via in the board which connects to the VTT voltage. The Vmem approach of just adding resistance between this point and pin 7 (VTT sense, or BT_sen) doesn't work, since the internal resistance to ground of the W83303D pin 7 is too large. Basically I connected small gauge wires to pin 7 and the MC50 pad closest to the W83303D (after cutting the trace connecting them). Mount a 1k pot in a convenient place and connect these wires to it. Solder a fixed resistor (approximately 8k-10k) from pin 7 to ground. I found it convenient to solder it to the pot rather than to pin 7 directly. Increasing the pot's resistance will now increase VTT. Once this pot and the Vmem pot are both set VTT and Vmem will track properly when the voltage is changed in the bios.

This mod will be difficult to do without the proper equipment. Soldering to pin 7 is especially difficult to do without a very fine tipped soldering iron and using magnification. Shorting pin 7 to adjacent pins will probably be disastrous. Obviously cutting the pc trace from pin 7 to MC50 must be done carefully. Standard disclaimers apply.

hipro5, pm or email me your email address and I'll email you the W83303D datasheets.

How come my VDD voltage is not fluctuating? It is stable.

[jdmcnudgent]

so if im getting this correctly, you totally take out the old resistor. then use those two wires, and they get soddered to the legs of the pot, and your done?? which leg of the pot does not get used?? i am getting this board on friday, and im gonna modd it right outta the box, i want an extremely high oc.

[jdmcnudgent]

anyone know the exact part number that i need from radio shack??

[hipro5]

Originally posted by jdmcnudgent
anyone know the exact part number that i need from radio shack??

You can solder a trimmer(10turns).....The midlle pin of it and one of the others(doesn't matter which).....300 Ohms trimmer......

[cpulloverclock]

Originally posted by Yozza
I shall be trying this mod out on my IC7-G as soon as my 3.0GHz 800FSB P4 arrives.

How much difference would the VTT mod make though? ... as the termination voltage should be half of the DDR voltage.

My board seems to have DDR voltage fairly smack on the BIOS setting though. Winbond HW Doctor is reporting 2.80V (with ocassional jumps to 2.78 and 2.82) when 2.80 is selected in the BIOS. VTT is at 1.38 - 1.40V.

What it is reporting wrongly though, is my CPU temperarature - 63C under load at 3.06GHz P4 with the big stock cooler. The P4G8X I had previously was reporting ~50C under load. Seems a common problem with all ABIT boards, and this IC7 is no exception as many have discovered

my VTT voltage is at 1.61v when I choose 1.65v for the vagp

vagp 1.65v = VTT 1.65v = vagp 1.37v
It's strange

[bmg]

Yes the display of Vagp and Vtt are swapped. Abit has been notified of this.

[cpulloverclock]

Originally posted by bmg
Yes the display of Vagp and Vtt are swapped. Abit has been notified of this.

ok I understand

last question

What is the vmem mod for the SI7
I don't find the R50 resistor



It's still the same mod?

[jdmcnudgent]

Originally posted by cpulloverclock
ok I understand

last question

What is the vmem mod for the SI7
I don't find the R50 resistor



It's still the same mod?

you wont find it for the si7. this is for the ic7. by the way, i need more info, what om pot do i need from rs?? it was like hipro was speaking tounges when he responded.

[nikhsub1]

Originally posted by jdmcnudgent
you wont find it for the si7. this is for the ic7. by the way, i need more info, what om pot do i need from rs?? it was like hipro was speaking tounges when he responded.

He is saying that you need a 1K VR... either a trimmer VR or a Cerment pot, set to 300Ohms. Radio shack has the 1K trimmer VR's, not sure about the Cerment pots though.