If I overvolt my 5V rail will that increase the voltage to the memory?
Printable View
If I overvolt my 5V rail will that increase the voltage to the memory?
If you are using a DDR booster, I think that increasing either the 5v or 12v rails will increase the Vdimm, but I also think that increasing the voltages screws with the voltage readout on the DDR booster as well.Quote:
Originally Posted by HiJon89
Whatsn the max voltage you can go now? I should measure the voltage with a multimeter to start, normally is you connect gare and drain to 5v, (like when to pot is turned to max) you'll get 5V- voltagedrop of the mosfets as vdimm...
How much vdimm you have now? measure with MM if you can? If your pot is already turned to max, then you can the gate and drain on the backside of you booster, I think this will give a little more, but if you still want more unsolder the +5V pin of the pot and connect it to +12v, this way, you'll be able to let the fets conduct soem more...
When turned all the way to the right it says 3.5V idle 3.4V load. This is with 12V rail at 12.1 and 5V rail at 5.1.
Can you measure what voltage you get at the gate pin of the mosfets?
Was that question for HiJon89 or me? If it was for me, I get about 7.5v on the gate, with 3.7v Vdimm, but it varies with the ammount of load on the Vdimm supply. If the question was for HiJon89 please ignore this post :p:Quote:
Originally Posted by Rub87
It's impossible to get 7.5v on the gate as the booster only gets feed by +5 and -5v... there is no 12v line to the booster so it can be max +5v...
Question was for HiJon89 :D
The gates are fed trough the pot from the +12V line ;)
Crap, now I see again, You're right, I verlooked the +12v
Hmm,
Installed windows, flashed the D25 merlin bios..
Actually I get pretty much fluctuation in Vdimm, goes when @ 3.5v in bios it goes to 3.38 sometimes when running sandra membench, 5v line drops fron 5.07 to 5.01, prolly that's the cause of the huge Vdimm drop, any ideas to make it more stable? The good news is: when running 1 gig BH-5 @ 3.7v, the IRF640 gets warm, but not hot.. (used a Hell of a Heatsink) :toast: I need the cable of my camcorder, or my digicam should revive so I can post post some pics!!
How long is the cable between the gate pin and the OPAMP? I've found that I get the most stable voltages with a very short wire between the 2 points.
Also, what is the gate voltage at? It should vary depending on the load on the regulator, and check that the reference voltage from the pot isn't varying (you could put a small capacitor between the non-inverting input and ground to help stabalise the reference voltage and provide "soft start" at power on. 0.1uf should be ok.
The wire between the OPAMP and gate is around 30cm...
The reference voltage is 5v, so it varies quite a bit...
The gate voltage is between 6v and 8.5v, I'll ad some capitance soon ;)
The gate cable might be too long. I'm using a 5cm piece of sheilded audio cable on my regulator. The gate pin is very susceptible to noise.
You could also try taking the feeback between the Vdimm output and the inverting input of the OPAMP from a point connected to Vdimm on the underside of the Dimm sockets, which will help to compensate for any voltage loss in the cable between the output of the MOSFET and the Dimm slots.
Shortned the gate wires, added some 10µF to the wiper wire...
Soldered the feebback lines where the original vbt/vtt mosfet was...
Now the voltage drops from 3.52 to 3.48-3.49 when applying load.. If I want it perfect, my 5v don't may fluctuate or I should need a perfect stable external suplly for the pot that isn't load dependent...
You could try regulating the 12v line down to 5v using a zener regulator to provide a stable 5v supply for the pot.
http://drunken-student.co.uk/tom/mods/5v1reg.JPG
Ideed, I think there must be lying some 4.7v zener's somewhere over here.. but where...
I don't get it anymore, It's not even primestable @ 220 dcddr :(
Was it prime stable before you re-built the Vdimm/Vtt regulator?
my booster droops pretty bad also.
without the booster
p4c800e-d bh-5 256x2
no load- 2.81V
load- 2.71V
with booster
no load- 2.95
load- 2.80
using prime 95 torture test for load.
antec 550 true control. all rails very stable.
that .1 seems like a huge droop for this thing.
Nope, 240 wasn't stable, didn't test 220..Quote:
Originally Posted by persivore
As I still didn't found my usb clable for camcorder, I made a movie and captured a few pics and captured them via i-DV firewire cable and then captured some pics in MM .. enjoy the crappy stuff:D
Btw, 215 seems primestable...
I remember that I was having similar problems to you when I first built my regulator, but I can't remember how I solved them. I think that I found that putting a capacitor and resistor in parallel with each other into the feedback loop helped, but I'm not 100% sure.
Try putting a 1k resistor in parallel with a 100Nf capacitor and put that between the non-inverting pin for the Vdimm supply OPAMP and the Vdimm supply output on the MOSFET.
I'll try to think of some more ideas later and try breadboarding some of them.
Quote:
Originally Posted by persivore
Don't have such small caps, any source for such small ones out of old hw?:/ ..
What problem do you mean? that it isn't stable above 215 fsb? or the minor fluctuation between load and idle? When I've time I'll check the generated current with a scope? Do ypu have some info about how to use one? my dad has one but I don't know how to use on a effecient way...
You could try finding a 1uf capacitor on an old motherboard. I just looked at one thats next to me and its got a few of them on. Just replace the 1k resistor with a 100ohm resistor. The exact values of the componens shouldn't matter too much tho tbh.
You might also be able to fund a 100Nf capacitor inside an old PC power supply (could also be marked as 0.1Uf).
I was having the problem of the fluctuation between load and idle. I think that it might have been up to 0.3v when I had the problem tho.
With the scope you can measure the voltage fluctuation. Connect the ground lead to a good ground point on the motherboard, close to the Dimm slots. Connect the + lead, via a capacitor (value shouldn't be too important as long as it isn't too big) to the Vdimm supply. The capacitor should act to block the DC voltage, and just leave the AC 'ripple'/voltage fluctuation to go to the scope.
Allright, I'll give it I try somewhere in the next few days... The voltage fluctuation between load and idle is only 0.03v and the prime errors comes after 2-3min or so...
But when I check it with the scope it'll become more clear, btw, what Vdd are you running?
I don't use my NF7-s much any more, but I've had it prime stable up to 245MHz FSB with 2*512 Tccd with CPC on, 2.6v. I was running 1.7v Vdd, but anything over that didn't benefit me. I couldn't get it 3d stable above 250 with 2 double sided sticks of RAM, but I can bench at 260 with 1 stick in single channel.
I can bench sandra op to 255 dcddr, cpc on, get around 3750, due sucky 2ghz cpu speed...
Anything aboive that result in reboot while test...
I've an infinity to, but riped of the LM358..
It died due some problems with vcore after some bad ocp mods with those 3 little smd resistors...
Is it also possible to work out a vcore supllie the same way? Problem is, there is pretty much damaga around the vcore area :)