P4C800-E droop mod - Does the resistant matter? - Zero resistant

[deltarealm]

P4C800-E is droop modded with 50k VR set at 28k. That was not enough, I slow worked VR all the way to zero. Is this safe?

This is how it stands with bios set at 1.55v tested with dual prime95, and motherboard monitor:

Without mod = 1.6v idle, High = 1.6v / Low = 1.47v - total change 0.13v

VR set at 28k = 1.62v idle, High = 1.63v / Low = 1.55v - total change .08v

Still seem to much of a droop. Lowered the resistants more, the droop gap closed but not by much.
Keep turning the VR, before I knew it, I was at Zero.
At zero it is much better:

VR set at 0k = 1.63v idle, High = 1.65v / Low = 1.6v - total change .05v

Appears that zero resistant is the best setting/balance, and lowest change in voltage flux.
Can I safely run at zero?

[persivore]

Are you checking the voltage using software or with a multimeter? Software readings are almost always inaccurate, so try using a multimeter to find what the true Vdroop is like.

[deltarealm]

Where do I messure that at with a mutlimeter?

I never would of thought, but zero on the VR, didn't think the board or CPU would still be alive.

As far as the software readings goes. Funny as it may sound, zero looks in no doubt with my particular board the right setting.

[persivore]

You should be able to get a Vcore reading from one of the chokes/inductors near the CPU socket.

[deltarealm]

Nice thanks for the tip, don't think I can get to the base of one of those coils anyway.
I wouldn't be able to sit there for 12 hours while running prime95 and 3D apps, noting the high and lows of the voltage reading.

PC has been on for 24 hours now at zero, and everything is ok.
Is it safe to run at zero resistant?

[persivore]

Nice thanks for the tip, don't think I can get to the base of one of those coils anyway.
I wouldn't be able to sit there for 12 hours while running prime95 and 3D apps, noting the high and lows of the voltage reading.

PC has been on for 24 hours now at zero, and everything is ok.
Is it safe to run at zero resistant?
You only need to check the voltage difference between load and idle to see how bad the droop is. The droop problem could also be due to your power supply.

I think that on some regulators it is possible to get 'possitive droop', where setting the resistance of the droop resistor too low will actually result in an increase in voltage under load. If this is the case with the P4C800, it could damage something.

The droop mod for the P4C800 has been widely tested, and a value of 28k has been found to be the best value resistance to use. If you need such a low resistance as you are using, it would suggest that there is something else causing the droop, or the mod isn't working properly.

[deltarealm]

Should be working, I done my bit perfect without a doubt. PS is an enermax 550w, never had a problem with it, voltage line are all good.

Do you have a picture you can post here, then I can take a reading on the Vcore on the board.
None of the places I have visited on the web show where to take a Vcore reading.

[persivore]

Check Vcore where I've marked. The inductor I've marked is one of the ones at the top of the board near the P4 power connector.

[heater918]

With vr@ 28k Bios setting 1.585Vcore 3.4EE@ 230 fsb 3.9 MHz PC P & C 510 Express
Load= 1 Prime large +D2ol

Read on inductor leg closest to cpu socket as marked above.
Idle 1.64
Load 1.62

CPUZ
Idle 1.58
Load 1.60

Everst
Load 1.55
Idle 1.57

Probe
Load 1.58
Idle 1.60

Monitors all report various readings. I'm going by inductor readings, although there is large varience in bios setting & inductor V's.

My G5 mount plate makes it hard to get to, try coating length of copper wire with liquid electrical tape leaving 1 small end bare. Or these extensions from radio shack or great. You can clip on with small hook or press on probe to expose small end .

[deltarealm]

Still haven't got around to testing the voltage on the board, wires, bunch of fans bolted around the area. I would assume it be ok, running an EE cpu, I know at ~1.75v and above it becomes unstable before the mod, so there is not to much voltage going into it, also can tell by the temps.
It is more stable at zero resistant than 28k or 13k, or whatever in between 28 and zero.

Actual question has not been answered yet, is zero resistant ok?

[heater918]

I would think set a zero you would be at or close to point with no mod. 1.75v imo is to high with out phase change, with mod you will overvolt somewhat at idle and that will push your 1.7v higher. That may be why it's more stable turned down. You really need to read with MM to be sure. I posted above just for some comparison notes, I'm new to Vmod's & following your experiences for info. Not meaning to spam your thread. Try long wire coated with liq.tape you can bend it in any shape & not worry about shorts, Good luck.

[deltarealm]

I have gone ahead with the mutlimeter test, over volts only .02v, thats fine for me.

I have upped the bios voltage from stock 1.55v to 1.6v in order to obtain a higher stable overclock of 3.7 GHz:
VR still at 0 k.

Motherboard monitor:
Droop mod with bios set 1.6v: VR set at 0k = 1.68v Idle, High = 1.7v / Low = 1.65v - total change -/+.05v

Multimeter:
Droop mod with bios set 1.6v: VR set at 0k = 1.68v Idle / 1.7v Load - total change +.02v


I think that is a good result with the mutlimeter, I rather a slight increase in voltage under load than a reduction. For a Extreme Edition CPU on water cooling 1.7v should be fine

[CaTalyst.X]

I have never tried 0 resistance..but are you reading that resistance with the VR soldered in circuit or before it is soldered on? I would say..take the mod off and set to 28K, solder the VR back on and give it another shot.

-CaT

[deltarealm]

Multi turn blue 50k VR, set to 28k before soldered to the board.
I checked many many times that everything was correct and soldering was perfect.

- Before the mod, my board was over volting at idle anyway.
- After mod, it over volted slightly more at idle, droop had improved, though still far to much droop to put up with.
- Slow turning the pot towards where zero would be (I know some of these blue multi-turn VR's don't reach absolute zero, but close enough), the droop started to improve.
- At where I am now, appox 15 turns anti-clock wise till I feelt the VR make a click sound indicating pot is at its limits. Believe it or not, seem to be the best setting for me.

lol, I will not be taking the board out a third time, my case has many many wires, water tubes, bolt on parts, and mods, to do it all over again.
If I did take it out, I would remove the droop mod and run the CPU at a lower speed, then that way it would droop all the way down to 1.47v and run very cool.

Droop mod, only really good for ~100 MHz, if that. More power = more heat, so you really cannot win, unless you got super cooling.
I brought this board with the intention of getting more MHz out of the CPU, though buying this board defeated the purpose, its performance 1:1 sucks compared with an Abit GAT board I was running. Its latency is 12% faster at 8fsb lower.
The only thing I can hope for from the Asus board now is added 4x 512MB of BH-5, and that will likely be only obtainable at a low clock speed.

[deltarealm]

Multimeter test @ bios 1.55v

Idle= 1.63v
Load = 1.65v

[heater918]

The reason for droop mod for me & others was under load Vcore dropped so low i'd get re-booted. It won't increase max. MHz of cpu only increase stability IMO. Your MM reads compared to bios setting are like mine. That is what puzzles me why such a difference? I have stock rev.1 & i'm going to check bios Vcore & read value with MM to see how much it varies. 4 sticks of ram disables pat, no big lose IMO. Your BH-5 will probably surpass the gains pat gives you.

[deltarealm]

I have turned back the VR and added some resistance.
This time I have messured the Vcore on the board (going to stick to this way of reading voltage), and adjust the VR till the idle voltage is absolute equal to the the load voltage.
Good idea?

[heater918]

Getting idle & load v as close as possible. Testing like you are you will find sweet spot for your rig. What do you set agp v to?

[deltarealm]

Vagp at max 1.8v

I have 1.5 GB of BH-5, so I need all the NB can give. 3.4v Vdimm.
Able to run stable at 225 MHz with PAT enabled (have to use the 865 tweaker to enabled it, otherwise automatically disabled with 4 sticks).
All I need now is to find enougher GB of Mushkin 3500 Level 2, then I can get max performance mode from the memory. 1.5GB goes into a lesser performance mode than 1GB alone.

Bios at 1.55v (stock of cpu), = 1.6v Idle without mod.

After tweaking the VR, now have no change in Idle and Load, no matter what voltage I set at.
Bios at 1.55v = 1.634v with mod - Idle/Load.\

Unfortunatly I cannot select a lower voltage other than stock, no option to step it down in the bios.

[heater918]

Ah yes forgot about enable PAT with tweaker :up: Are you liking mobo better now?
Vgap mod next?

I'm just now playing with 3.4ES, 1GB. G.SKILL DDR550 LE. Drop multi.& shoot for 300+ FSB.