Vdimm mod for the P4C800 ???

**~~Amoeba Assassin~~** · 06-07-2003, 09:51 AM

thanks

**DJD** · 06-09-2003, 10:23 AM

Tried it in the P4P800 Deluxe (thanx to Hipro5) but has a problem. When it boots it gives the max voltage at all lines and thats something asus doesnt like. When it reads more than (equal to) 3volts at ram it just dont boot or it boots one in ten times.. Have anyone else experience with the P4P800 mod?

**Major** · 06-10-2003, 09:00 PM

Was the mod for the P4P800 the same as the P4C800 ??

Maybe they have overvolt protection on the P4P ?

**DJD** · 06-10-2003, 10:05 PM

Originally posted by Major Slaughter
Was the mod for the P4P800 the same as the P4C800 ??

Yes it was the same but the spot you had to mod is in different place.

Maybe they have overvolt protection on the P4P ?

Maybe...

**dstanley** · 06-11-2003, 12:58 PM

Originally posted by Major Slaughter
This is the best I could get out of her stable, 240mhz 1:1 2.5-4-4-8 @3600mhz.

I'll probably leave it at this for a while, I lost 120mhz on the OC by going with 1:1 instead of the 5:4 divider, but my memory bandwith is alot higher and the system "seems" more robust. + I'm able to do this at 1.6v vs 1.7v

Also the New beta bios v1007.006 rocks !!!! really improves memory bandwith and seems just as stable if not more so than v1006

Have you done a step by step to building your PC, it seems to be pretty similar to mine.

Also any1 find a step by step guide to installing this Vmod? I have a few friends after doing electrical engineering in college, probably best to get these to preform any mods to the board?

I just need to tell them to do what with what basically.

**Blue078** · 06-11-2003, 02:23 PM

Originally posted by dstanley
Have you done a step by step to building your PC, it seems to be pretty similar to mine.

Also any1 find a step by step guide to installing this Vmod? I have a few friends after doing electrical engineering in college, probably best to get these to preform any mods to the board?

I just need to tell them to do what with what basically.

Solder 2 wires, one to the middle leg on the VR, and one to anyone of the other two legs on a 50K VR.

Then solder one wire to pin6 of the LM358 IC, and the other wire to pin 4. simple and effective.

Be sure to set the VR to it's max 50K ohms with a DVOM to start off with. Besure to turn the VR very slowly when adjusting the VDIMM

**shogan191** · 06-29-2003, 06:28 PM

If someone could confirm my understanding I'd appreciate it.
On a P4c 800 Deluxe I take a 47K pot. solder a wire on the single leg, another wire on one of the two legs on the other side. Solder one of those two wires to pin 6 as shown in the photo and the other to pin 4 as shown in the photo. It doesn't matter which wire goes where. I do this with the ram out of the machine and the bios settings to 2.55 the lowest setting. When I power on machine I test the voltage at the other location in the photo and get a read on where it is compared to where the bios was set. I should be able to adjust the adjustable pot and monitor the change with my meter. I want to set the reading at the voltage check point to 2.8. That is .3 higher than the bios says and it will remain .3 higher than the bios reads as I change the bios setting. So tht when I have the bios set to 2.85 it is really 3.15. I hope that is right I've been reading this thread for about 3 hours now.

**Blue078** · 06-30-2003, 05:14 AM

Originally posted by shogan191
If someone could confirm my understanding I'd appreciate it.
On a P4c 800 Deluxe I take a 47K pot. solder a wire on the single leg, another wire on one of the two legs on the other side. Solder one of those two wires to pin 6 as shown in the photo and the other to pin 4 as shown in the photo. It doesn't matter which wire goes where. I do this with the ram out of the machine and the bios settings to 2.55 the lowest setting. When I power on machine I test the voltage at the other location in the photo and get a read on where it is compared to where the bios was set. I should be able to adjust the adjustable pot and monitor the change with my meter. I want to set the reading at the voltage check point to 2.8. That is .3 higher than the bios says and it will remain .3 higher than the bios reads as I change the bios setting. So tht when I have the bios set to 2.85 it is really 3.15. I hope that is right I've been reading this thread for about 3 hours now.

That pretty much sums it up

I dont know were the other guys came up with adjusting it with out any memory installed??

I tried and their was 0 voltage in the dimm slot or at the MOSFET.

So I did the first {test} adjustment with an old stick PC 2100 in one of the dimm slots

**mrzee** · 06-30-2003, 07:42 AM

Just did the mod, really quite simple, took about 20 minutes.
At 2.85v in bios, I got 3.15v.

**Blue078** · 06-30-2003, 08:47 AM

Just be sure to turn the POT slowly when you adjust for even more vdimm

**mrzee** · 06-30-2003, 09:04 AM

250fsb, 1:1, vdimm3.15v

**Blue078** · 06-30-2003, 09:21 AM

NICE very NICE. Good timnings too

**shogan191** · 06-30-2003, 01:46 PM

Thanks for the confirm. Guess there is nothing left but lllllllllllldoit.

**NyCUndaGrounD** · 07-08-2003, 01:43 PM

I hope i did mine correctly on the p4c800-e.
47k ohm pot

**markodude** · 07-23-2003, 12:36 AM

Hehe, another overclockers.com member is here to bum advice of you xtreme experts!!

OK people, got my 47k VR from Maplins yesterday, no-one seems to know WTF SMD grabbers are there though! Anyone got a pic of one?

I have a couple of questions -
1 - Is the middle post on this VR the ground? If so I take it I can use either of the others as the second post and one stays blank?
2 - How do I know what the max and min settings are? I am guessing that when the bit inside that turns touches the post the wire is on, that is 0 resistance and when it is touching the other one (that I wont have anything connected to ) it is at maximum resistance?
3 - What do Maplin call SMD grabbers??

Thanks in advance people

**markodude** · 07-30-2003, 12:00 AM

OK thanks for the help people, I got the VR soldered up and am about to order a Pomona SMD Grabber rather than soldering....

**Major** · 07-30-2003, 12:17 AM

markodude welcome to the Xtreme !!

Glad to see you here !

It appears you earlier post got burried !!! sorry nobody responded to it. I hope your mod goes well, post some results when you are through !

**markodude** · 08-02-2003, 01:03 AM

3.25vDIMM

3.15vDIMM, alllows me to tun my CPU at its usual setting where I used to have to run RAM at 2.5-6-3-3

Pin 6 - I used the same one as the rest of you but still cant work out how it is pin 6
vDIMM can be measured with no RAM in the slot
Board overvolts by .1v on vDIMM during boot process.
Max voltage I used was 3.35v and I could not get DDR533
Cheers peeps

**markodude** · 08-02-2003, 01:04 AM

Yeah, I need to get my other stick back from my mate to see if dual channel works....

**DoGMaN** · 08-03-2003, 07:00 AM

Has anyone measured to see what fixed resistor will give an offest of +0.3 to +0.4?

**Major** · 08-03-2003, 07:52 PM

DoGMaN, I did and posted it somewhere in this thread ! just have to look

**adad** · 08-05-2003, 12:14 AM

I just came back with 8 pairs of SMD grabbers, 100 meters [!] of single core wires, some 15 turn 1K pots and some 18 turn 10k as well.

Most of the people here are using either 50K or 47K pots.

Please tell me I did not buy the wrong pots - [no big deal, just need to run out again]

If this is ok, anything that the gurus need to point out to this voltmod newbie?

Thanks all.

**RootX** · 08-05-2003, 12:46 AM

Since the mod is the same for both p4p800 and p4c800, I assume that same resistor values produce the same voltages to both mobos.
I have a p4p800.

Roughly,(some finetuning may required) with a 15K resistor you get an .2 offset, while with a 10K resistor you get a 0.3 offset.
Now, if ur going for the 0.3, your 10K pot will be ok. If u go for the 0.2(and don't wanna buy a new pot) you can solder 2 10K pots in series and have a 20K pot, which will give you plenty of finetuning options, lol.

**adad** · 08-05-2003, 01:06 AM

Originally posted by RootX
Since the mod is the same for both p4p800 and p4c800, I assume that same resistor values produce the same voltages to both mobos.
I have a p4p800.

Roughly,(some finetuning may required) with a 15K resistor you get an .2 offset, while with a 10K resistor you get a 0.3 offset.
Now, if ur going for the 0.3, your 10K pot will be ok. If u go for the 0.2(and don't wanna buy a new pot) you can solder 2 10K pots in series and have a 20K pot, which will give you plenty of finetuning options, lol.

Thanks RootX for your prompt reply.

I have the P4P800 as well! I posted here coz I understand that the mod is similar to P4C. So if I understand correctly, 10K pot is fine for .3 offset, and two 10K soldered [three feet together with the turns aligning? Or facing opposite directions? Or don't matter?] will give me 0.2 offset.

And when i adjust it, I just need to turn ONE of them, is that right?

What about the 1K? So are they useless to me now?

TIA

**RootX** · 08-05-2003, 02:01 AM

I guess the 1k are useless, unless you wanna solder them altogether - kiddin'.

Now, in order to solder the 2 pots together, what u have to do is turn the litlle screw all the way till it can't go any further, and measure the resistance between the middle terminal and the other two.
One measurement will show 10K while the other will be 0.
Do the same for the 2nd pot.
What you have to solder is the terminal from the 1st pot that you measured the 10K resistance, with the terminal from the second pot that u've measured the 10K resistance(not the middle ones, but either the right or the left, depending on which gave you the 10K).
Now, as for the mod part, u have to solder the middle terminals from the two pots; one to ground the other to the 6th pin of the LM358.
By adlusting one screw of the two, you'll have a min of 10K, if you need to go below that, then you'll have to adjust the second screw.
But please, before connecting the terminals to the IC or ground, measure with a multimeter that the resistances work as expected.

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