OCZ DDR booster 'droop' mod

[persivore]

Thanks to:
bachus_anonym and bh2k for pictures (please don't take the choice of pictures personally )
Rub87 for input and ideas
The stick of 2700 Samsung TCB3 which died when 5v was put through it during the testing of the mod

Materials required:
LM358 opamp
10k variable resistor (multi-turn)
4.7k fixed resistor
15k fixed resistor
100nf capacitor
some sort of strong glue to attach the variable resistor and opamp to the DDR booster's PCB
A DDR booster!

Additional components for the more complicated mod:
5.1v zener diode (any power rating will be ok)
470ohm fixed resistor
100nf capacitor

Basic mod:
The basic mod is the easiest way to do the regulation mod on the DDR booster. This mod uses a reference voltage which is taken from the 5v rail, so could be influenced by fluctuations on the 5v rail.

1.The first step is to remove the variable resistor (VR) on the DDR booster. If you want to re-use the VR, instead of replacing it with a multi-turn VR, be careful not to damage it whilst removing it.

2.You must now set the VR to work as a voltage divider, which will be used to provide the reference voltage for the Vdimm supply. If you are using a different variable resistor to the original, use a multi-turn type. The 4.7k and 15k fixed resistors are used to make the boosters supply variable between 2.5 to 4.3v. Connect the 15k resistor to ground, and the 4.7k resistor to the 5v supply rail on the booster, as shown in the picture. Connect the variable resistor between the free ends of the 15k and 4.7k resistors. Fix the variable resistor to the boosters PCB using glue ('super glue' as it is known in the UK works well. I think it is called 'crazy glue' in the US, but its a cyanoacrylate based glue)

3.To help stabilize the reference voltage from the voltage divider, you need to connect a 100nf capacitor between the VR's wiper and ground. This also provided 'soft start' to the Vdimm supply to help reduce the inrush current at power-up.


Hi-res picture


4.Next, get your opamp, and attach it to the DDR booster PCB, using the cyanoacrylate based glue based glue. Pin 1 of the opamp will be marked with a dot, or there will be a U shaped notch at the top of the chip - pin 1 will be to the left of the notch with the notch facing upwards. Connect the opamp via pieces of wire as shown in the picture - ground on the boosters power connector to pin 4 (ground on the opamp), 12v to pin 8 on the opamp (the opamps power supply pin), the variable reference voltage from the VR to pin 5 of the opamp (the non-inverting input), the middle pin of where the original variable resistor was connected to pin 7 (the output pin) and the output of the MOSFETs on the booster to pin 6 on the opamp.


Hi-res Pic

If anyone is interested this is the circuit diagram for the basic mod.


Complicated mod:
The more complicated mod uses a regulated voltage which is taken from the 12v rail, so the reference voltage isn't affected by the fluctuation of the voltage rails as much.

1.The first step is the same as the basic mod

2. To produce a regulated voltage for the reference voltage you need to use the 470 ohm resistor and the 5.1v zener diode. Connect the 470 ohm resistor to the 12v rail. Next, connect the end of the zener diode with the bar/stripe to the free end of the 470 ohm resistor. Connect the free end of the zener diode (the free end shouldn't have a stripe on it) to ground. Connect the 100nf capacitor in parallel with the zener diode. This will produce a regulated voltage of 5.1v. Make sure you connect the diode the correct way around otherwise it will produce a 0.7v regulated voltage


Hi-res Pic

3.You must now set the VR to work as a voltage divider, which will be used to provide the reference voltage for the Vdimm supply. If you are using a different variable resistor to the original, use a multi-turn type. The 4.7k and 15k fixed resistors are used to make the boosters supply variable between 2.5 to 4.3v. Connect the 15k resistor to ground, and the 4.7k resistor to the junction between the 470 ohm resistor, zener diode and capacitor, as shown in the picture. Connect the variable resistor between the free ends of the 15k and 4.7k resistors. Fix the variable resistor to the boosters PCB using glue ('super glue' as it is known in the UK works well. I think it is called 'crazy glue' in the US, but its a cyanoacrylate based glue)


Hi-res pic

4.To help stabilize the reference voltage from the voltage divider, you need to connect a 100nf capacitor between the VR's wiper and ground. This also provided 'soft start' to the Vdimm supply to help reduce the inrush current at power-up.

5. Connect the opamp via pieces of wire as shown in the picture - ground on the boosters power connector to pin 4 (ground on the opamp), 12v to pin 8 on the opamp (the opamps power supply pin), the variable reference voltage from the VR to pin 5 of the opamp (the non-inverting input), the middle pin of where the original variable resistor was connected to pin 7 (the output pin) and the output of the MOSFETs on the booster to pin 6 on the opamp.


Hi-res pic

This is the circuit diagram for the more complicated mod.

Before you power up the booster, check all connections (as I'm sure you will all do anyway ). Power up the booster by just plugging in the Molex/ATX connector plugs and not into the motherboard dimm slot, to check that the booster is working properly. Be careful not to let it short on anything when you do this. Check that the booster is producing the required range of voltage when the variable resistor is turned, using a multimeter or the display on the booster.


This is the modded DDR booster. Under load, the droop was found to be 0.01v with 2*256mb sticks of RAM with 3.6v Vdimm on an NF7-s


There are some compatability issues between some motherboards and the modded booster.

These are boards which the modded booster has been found to work with:
Abit NF7-s v2
DFI Lanparty UT NF3
Abit AS8 (Max. displayable voltage on booster and from software is 3.5v)

These are boards which the booster has been found to not work with:
MSI Neo2 (Nf3), however the same board has been found to not work with a un-modded booster, so there could be an issue between other components, and not the modded booster.

[Ubermann]

God job persivore!
When i search for the opamp i come up with 2 different ones.
They are named LM358N DIL8 and LM358D SO8.
Do they have same function ?

Another question, can i solder the capacitor to ground on VR even when not doing the mod to get rid of the jump start ?

[persivore]

The LM358N will probably be the best one to go for. They will both do the same job, but the LM358D SO8 might be in a different layout/package to the other one.
You can add the capacitor in without doing the mod, but I don't know how much benefit it will have. The capacitor isn't required in the mod tbh, but I added it to add extra stability.

[rhino56]

sweetness man thank you

[bachus_anonym]

Excellent guide, persivore :thumbsup:

[gbglassen]

great job persivore! Q: Can I use a higher value of the capacitor, such as a 10uF 16V?
or what kind of capacitor should I look for? thx

[persivore]

great job persivore! Q: Can I use a higher value of the capacitor, such as a 10uF 16V?
or what kind of capacitor should I look for? thx

The 10uf capacitor might give too much of a 'soft start' to the Vdimm supply, so the voltage might rise too slowly and the voltage adjustment via the pot might be a bit slow. Any capacitor of between 100nf (0.1uf)to 1uf should be ok. This sort of capacitor should be ok.

[Ubermann]

If i choose to not use the fixed resistors can i make it like it is on this pic then ?
They are only there for safe volt limits or ?

[persivore]

You can do it like this (check the picture). The voltage will only be adjustabe between Bios Vdimm to 5v tho, and most of the the turn on the variable resistor will have no effect because you will be varying the output of the booster below the Vdimm voltage set in the BIOS, so the on-board voltage regulator will take over from the booster.
If you do it this way, be careful not to set the booster voltage too low (below about 1v as it might short out the Vdimm regulator on the motherboard (I'm not sure about that tho)

[persivore]

I've just recieved some information. With the booster in a Neo2 where the board refuses to boot with the modded booster in. I've tested the modded booster in an NF7-s and worked it ok. I'm working on the problem atm and will post back if there are any updates.

Edit: The booster has been tested in another NF7-s and its working ok.

Edit2: There is a comfirmed compatability issue between the modded booster and the neo2. There might also be other boards with issues with the modded booster but I am unable to test any other boards. If you attempt the mod, you do so at your own risk and I cannot guarentee compatability between any boards.

[Ubermann]

Will try it this evening on DFI NF3

[persivore]

Will try it this evening on DFI NF3

If you try it, be careful not to put too much voltage into the board to begin with, to reduce the chance of damage to anything if there is a compatability issue between the board and the modded booster. I don't think that anything was dammaged when the booster was tested in the neo2, but there is always a possibility that it could happen.
Good luck! I hope it works

[Ubermann]

What resistance should i put on the 10K before i start computer without the fixed resistors ?
So i get btw 2V and 4V to start with.

[persivore]

What resistance should i put on the 10K before i start computer without the fixed resistors ?
So i get btw 2V and 4V to start with.

Setting it to 5k will give you 2.5v

[Ubermann]

Does it matter what way i solder the capacitor ? there is one leg going to "shell" on capacitor and one leg that goes inside it.

[persivore]

The leg which goes to the 'shell' is probably the negative lead, so you need to connect it to the ground. Connect the other lead to the middle pin of the VR.

Can you post when you have tried the booster. I'm trying to find out why there was a problem running the modded booster in the neo2, and knowing if it works in your board will help a bit . I've run simulations for the circuit and the only thing I can think of is that its some sort of protection that the neo2 has.

[Ubermann]

Will do, soldering now.
Have the sence of a little a-bomb smoke mushroom in my head but i hope it works.

*update* ITS ALIVE!

But i think the capacitor i choosed for this is way slow!
It takes seconds until it reacts.
Booster display does not match multimeter either.
But the good thing is that there is no droop what so ever!!
If i set it to 3.50V and restart computer it stays on 3.50 from boot until windows is started.
It did drop to 3.49 when superpi was running =)
Before this booster jumped alot when restarting computer like 0.3V sometimes releasing the OVP on motherboard.
Im very happy =)

*update* Done some more testing and there is no droop, not even 0.01.
The capacitor was an "backup" modell. Costed 8 dollars.
Can i kill something with that kind of capacitor ?
And how clever am i to solder first and ask later

[persivore]

Will do, soldering now.
Have the sence of a little a-bomb smoke mushroom in my head but i hope it works.

*update* ITS ALIVE!

But i think the capacitor i choosed for this is way slow!
It takes seconds until it reacts.
Booster display does not match multimeter either.
But the good thing is that there is no droop what so ever!!
If i set it to 3.50V and restart computer it stays on 3.50 from boot until windows is started.
It did drop to 3.49 when superpi was running =)
Before this booster jumped alot when restarting computer like 0.3V sometimes releasing the OVP on motherboard.
Im very happy =)

*update* Done some more testing and there is no droop, not even 0.01.
The capacitor was an "backup" modell. Costed 8 dollars.
Can i kill something with that kind of capacitor ?
And how clever am i to solder first and ask later

Thats great
I think it should be ok to remove the capacitor if its making the response too slow. Its main purpose was to help filter the voltage from the variable resistor if there was lots of noise from the 5v rail.

[Supertim0r]

I didn't performed a vdroop on my booster but when I switched the 1turn pot
to a high quality 25turn pot, it was WAY MORE STABLE

[Ubermann]

You would have an awesome booster mod if you manage to move the display to the front panel also!

If i remove the capacitor do i just connect the wires that goes to the capacitor with each other then ?
Err no i dont i just remove them right ?

*update* Removed it, still no drop what so ever.
Another note, i cant trigger OVP on motherboard ?

[jiff]

Got a booster coming would this pot be a good replacement?

http://uk.farnell.com/jsp/endecaSear...U=351593&N=401

Thanks for ya help

[Supertim0r]

Got a booster coming would this pot be a good replacement?

http://uk.farnell.com/jsp/endecaSear...U=351593&N=401

Thanks for ya help

this really look like the one I used
you should get it !!

[persivore]

Got a booster coming would this pot be a good replacement?

http://uk.farnell.com/jsp/endecaSear...U=351593&N=401

Thanks for ya help

This one would be better. Its the same as the one you linked to, but its resistance is 10k instead of 5k

Edit:

You would have an awesome booster mod if you manage to move the display to the front panel also!

If i remove the capacitor do i just connect the wires that goes to the capacitor with each other then ?
Err no i dont i just remove them right ?

*update* Removed it, still no drop what so ever.
Another note, i cant trigger OVP on motherboard ?

Its probably too late now, but just remove the capacitor and leave the points it was conencted between unconnected.

Did you have a problem with OVP before? What voltage were you able to go to, and what can you go to now?

[gbglassen]

I did the basic mod yesterday, biggest drop is now 0.03v.
Persivore: can I adjust my 12v and 5v rail without the booster going nuts if I do the advanced mod? thats the idea with the zenerdiode and capacitor isnt it?

thanks

[persivore]

I did the basic mod yesterday, biggest drop is now 0.03v.
Persivore: can I adjust my 12v and 5v rail without the booster going nuts if I do the advanced mod? thats the idea with the zenerdiode and capacitor isnt it?

thanks

Yea, the advanced mod will not be affected by you changing any of the power supply lines. What board are you using the booster on btw?