Vdimm with or without RAM?

[Private Joker]

I just VDimm modded my Mobo and I´m not sure what the right voltage reading is.
When I read the guide they say "messure VDimm without Memory". But I guess it is just because of security issues!? Is it?

Because, when I messure VDimm (at 2.55 in BIOS) without Memory its 3.0v, and with Memory its "only" 2.8v. So which reading is the right one?

Thx

[flapperhead]

if thats what they say then thats the way u measure it. although iwould think u want to see how much voltage is getting to the stix. actually u can probably get more info over at the volt modding section of this forum. maybe someone who has done it can help u there guy...

[Private Joker]

Yeah, I thought that, too. Its logical that the voltage with the sticks is the actual, but (as you said) I´d like to know it for sure. Because I could fry my memory with 3,3V, whereas I think that its 3.1V. :)

Whatever... Thx, man, i´ll try it in the volt-modding section.

[mrspec3]

I remember when I was testing with and without the memory I got different voltages. I always test now with this junk pc2100 stick just to get my voltages set before putting in any good ram

Steve

[Private Joker]

I remember when I was testing with and without the memory I got different voltages. I always test now with this junk pc2100 stick just to get my voltages set before putting in any good ram

Steve

Yes, seems logical to me. But do you really need junk sticks to set it? I mean: Max is 3.3Vdimm. Every good RAM should take this for a while. :)

[mrspec3]

Yes, seems logical to me. But do you really need junk sticks to set it? I mean: Max is 3.3Vdimm. Every good RAM should take this for a while. :)

Max for you maybe. I've been testing max of 4.2Vdimm....so not all stick can take that :attn:

[Clevor]

You can measure VDIMM with ram in, and in fact, it is best to check voltages under load. This separates the men from the boys.

What they mean is when using pots, you may have set them in the wrong direction so instead of starting low you are feeding them 3.3 volts from the gitgo or something. So then you want to check with no ram in first.

You're talking Asus P4C board right? Well the voltages are screwy with this board. Check VDIMM with a multi while running Memtest and you will see it maxes out at 3.0-3.06 under load despite setting up to 3.26 in the BIOS. Notice the errors in Memtest? Supposedly disabling USB Legacy in the BIOS solves this but it has never worked for me with 5-6 diff boards.

Then check VDIMM in Windows running 3D apps. It holds - more or less. 3.26 is more like 3.1, 2.96, 3.11, 3.0, 3.2 etc. Wonder why the CPU1 or CPU2 test tends to crap out in 3DMark2003 when you overclock too high? I see VDIMM dropping the lowest of any 3D app here.

When I test ram on the P4C now I ignore Memtest and just boot and try 3D apps. If it passes Sandra mem, Cache&Mem, Aquamark, 3DMark2001, 3DMark2003, and PCMark2004, hell I don't care if it errors in Memtest. Tested the same ram on Abit boards, if it shows ANY errors in Memtest, it's not 3D stable. Life is simple there.

And of course, the VCORE droop is another issue. Hopefully Asus has learned their lesson and their next generation of boards will be 4-phase with 3 mosfets per phase and 3500 u caps, a la the AOpen A4XC-MaxII. This is the best VCORE board I've used (but it has baaad memory issues).

I used to be real high on the P4C800-E, but after testing 300+ fsb chips in them compared to the Abit, I have my reservations. Don't get me wrong, I keep a P4C800-D and two -Es, and they run 5:4 best of any board, but Asus needs to get their act together with voltage regulation. If you look at the later Abit revisions of their boards, rails all overvolt. The AI7 I just picked up is overvolting VDIMM big time: 3.2 in the BIOS is 3.278 on a multi. The Rev. 1.2 IS7 I have is the only board I've seen where 1.675 VCORE in the BIOS shows as 1.675 in all Windows monitoring software. Abit is quietly working behind the scenes to improve in this area.

Sorry for the rant :temper:.

[NoteUser]

It depends on the POT setting. If your setting is 2.55 (BIOS) and the mod equals 2.8 that's .25 plus BIOS setting.

I would stick with the memory in reading. The in and out memory reading isn't too far off anyway, .2.

[Private Joker]

Thx clevor for explanation! :)

I´ll check it, but I noticed it doesnt make any difference for me, since my RAM wont run 2.5-3-3-7 at 255FSB at no voltage (max 3.3v in BIOS ;) ), so I keep it at 3.0v.

@noteuser: I notice no difference. The settings in the BIOS doesnt affect my VDimm anymore. The difference between 2.55 and 2.85 in BIOS is about 0.05v accual. But maybe a high voltage in BIOS it helps keeping the accual voltage more stable...

[Clevor]

The settings in the BIOS doesnt affect my VDimm anymore.

Is this via a multimeter? It should move at idle.

How well your ram responds is a different matter. While the ram with Micron -5B C ICs respond to more VDIMM via the pot, my BH-5 hardly budge. At '3.26' VDIMM in the BIOS, I can only do 238, 1:1, 2-2-2-5. With same voltage on Epox boards, I can do at least 250, 1:1, 2-2-2-5. :eek:

It's girly-boy VDIMM on the Asus, not He-Man stuff. You may have to boost the 3.3 rail way up with the Asus, or run a thick wire directly from the ATX power plug.

[NoteUser]

Your probably at the point where more voltage does nothing to the gold series.

The EB is said to respond to voltage but you'll need to cool them with 80CFM; that's the stuff that uses the Micron chip.

[Clevor]

I blow a 120 mm, 38 mm thick Sankyo Denki fan over my ram on all five rigs I got :D. To cool the ram better only way is to rig two 60 mm 6000+ rpm Delta fans over it but it will be a pain and damn noisy! Those things are like sirens.

[Private Joker]

Is this via a multimeter? It should move at idle.

How well your ram responds is a different matter. While the ram with Micron -5B C ICs respond to more VDIMM via the pot, my BH-5 hardly budge. At '3.26' VDIMM in the BIOS, I can only do 238, 1:1, 2-2-2-5. With same voltage on Epox boards, I can do at least 250, 1:1, 2-2-2-5. :eek:

It's girly-boy VDIMM on the Asus, not He-Man stuff. You may have to boost the 3.3 rail way up with the Asus, or run a thick wire directly from the ATX power plug.

Yes via Multimeter, there in no other way to measure it on my mobo, I think. I havent tried to measure it under load though, but I guess noteuser is right, voltages doesnt affect my oc anymore.
And, yes, I´m cooling it also with a 120mm enermax @ 2500RPM. :)

[Clevor]

2.55 VDIMM doesn't work on the P4C800-D anyway. It is the same as 2.65. However if you set the pot so 2.65 is 2.95 in the BIOS at idle, when you set 2.75 in the BIOS it should read 3.05 on the multi, etc. Make sure you have the pot on the right pins on the LM380 chip.

I also found increasing VDIMM didn't help much with Vitesta ram; it's not like I could get it to run 300, 1:1 at 3.26 volts. The only ram I seen it help is with the new Micron stuff, though only a tad at 1:1, mainly at 5:4. I have an AI7 up now and last night I was able to run 294, 5:4, 2.5-2-2-5 at 3.1 VDIMM with Crucial sticks.