[Mallet]

First read this http://www.vr-zone.com.sg/?i=757

here's a nice little solder point for a memory volt mod



Solder a20k ohm VR to ground from the point i soldered to in the picture, or you can solder to FB pin marked in picture. I used 50k but had to turn it way down so 20 should work good. Vddr measure point is the left leg, on the lower of the 2 mosfets right of the ddr/ddr2 slots.




***ADDITION*** Agp and northbridge volt mods

*****Update***** What we thought was the voltage for the Northbridge is in fact the CPU VTT. It is recomended to keep this voltage Below 1.5V (Thanks to JIMMOR for this update)

I have found both Vagp and Vnb(<---CPU VTT).

The voltage measure points for them are:
Vagp --> the upper leg of the mosfet between the pci-e slot and the agp slot. I had to take out my agp card and power up the system to check this voltage with the multimeter

http://www.atris.it/Forum/photoplog/...um/1_V-AGP.jpg
Thank You McTURBO for the picture

Vtt --> the upper leg of either mosfet between the northbridge heatsink and the 20pin molex connector.

http://www.atris.it/Forum/photoplog/...ium/1_V-NB.jpg
Thank You McTURBO for the picture



To raise Vagp shade the resistor shown in the picture from 1.88 k ohms to ground down to 1.75 k ohms for about 1.7volts. This was with agp set to normal in bios. Be carefull and check resistance before powering on, it only takes one or two pencil strokes as the resistance is high allready. This mod hellped me get past 306fsb to about 318fsb, I need to do some stability testing though, but before I could not boot into windows at 308fsb. I think I may actually be running into the limit my e6600 will do at 2.86ghz on stock vcore. **This mod will help get higher FSB.

To raise Vtt shade the resistor shown from 990 ohms to ground down to about 940 ohms to ground for about 1.4-1.45 volts, stock is 1.35v. (This mod is risky to cpu, It is recommended to stay below 1.5V, Thanks JIMMOR for the caution) **This mod can help memory timings.

Also some oc hints for the 775dual-vsta. In the Bios set:

Cpu:pci-e async
Pci-e 117mhz (use only with agp graphics card- can cause damage to pci-e cards)
spread spectrum - Disabled
V-link - normal
Pci-e downstream pipeline - Disabled (This setting fixes random freezing of 3D applications with some Pci-e graphics cards)

****EDIT****
1. added Vdimm measuring points
2. Corrected mislabled FB pin on RT9202 for Vdimm mod (Thank you Gentleman for pointing this out, page 22)
3. Corrected, what I thought was Vnb is actually CPU VTT (Thank you JIMMOR, page 22)

---

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So is it actually helping your overclock?

[Mallet]

Im at FSB 305 and Cpu Z shows my memory at 610mhz 3-4-4-8 1T. This is with 2 x 512MB of Kingston Value Ram DDR1. I'm giving it 3.01volts before I had to use a memory divider past around 280 fsb or it was unstable with only 2.73v to memory. The performance hit using a divider was huge, more than 30% in some benchmarks, plus I was not able to use the ddr400 setting at 1T I had to go to 2T. This wont help you gain any mhz on the FSB speed, but it will help if your memory is holding you back.

I plan on doing some stability testing and lowering voltage gradually till it becomes unstable then bumping it back up a bit.

I'm using corsair 6400 DDR2, I suppose I need a different point for DDR2? Anyway I haven't tested too much yet but at 290 i'm stable whereas 299 gives errors when doing prime blend test, but not on cpu only test. So either my memory is not getting enough juice or the memory controller is the problem.

[Mallet]

have you tried loosening your memory timings?

I've set my mem timings to the stock values, while it's running way below rated speed as it's 6400 DDR2. So the timings shouldn't be the issue. In fact if I set them to auto the timings are actually tighter and things still work

[Mallet]

Have you set "IDE Drive Strength" to "Highest". Also The only way I can get past 300fsb is to "Disable" , "PCI IDE Bus Mastering" This kinda hurts my hd performance though. I will try to post some more of the BIOS settings I'm using in a bit.

Where you are able to tighten your memory timings at 290 without causing problems. Your stability problems probably stem from the motherboard chipset. I'm pretty sure that my 306FSB limit is being caused by my harddrives or the IDE Controller.

Update on CPU-Z: It doesnt report the correct DDR1 frequencies with this board, however it reports the right timings. Clockgen 1.0.4.8 Beta reports the proper DDR1 speeds. So Im only running DDR450 but I brought my timings down to 2.5-3-3-7 1T.

I could try disabling the bus mastering, I only use a DVD burner on IDE, the rest of my drives are sata anyway, some on board and some on a seperate raid controller. Apart from that I very much doubt my memory wouldn't live up to it's specs so I'm pretty sure the problem is the chipset or the implementation of it on this board. Further testing will have to wait untill monday, as I'm not at home this weekend.

[Shamino]

thx mallet, this will help a lot of users seems to be crawlin with 775 vsta users everywhere

thx mallet, this will help a lot of users seems to be crawlin with 775 vsta users everywhere

Hi all

Its the first time i post here and i wish to say that you have here an nice community, full of friendly people. Also I wish to say that you have an awesome forum

I am another 775DUAL-VSTA user, and I think that will be more like me, because we have lots of people with good graphic cards and good DDR kits and we are not willing to give up of that. That board allow us to keep the "old" hardware and upgrade to the awesome Conroe . Its an ship mobo and i think that represents the icon of an board to overclockers, because its cheap and it uses "old" tech. Plus if we could manage to control fsb/mem ratio, Vcore and an FSB about 400 that will rock a lot of PCIe and DDR2 systems.

As it is now I could obtain the following results:





















So what do you think its an powerfull but cheap upgrade (about 195 € for CPU and 55 € for Mobo) from "old" intel and AMD systems, isnt it?

Today I tried turning off IDE busmaster and serial/parrallel ports as i'm not using them anyway. Eventually I even tried disabling the IDE alltogether but everything to no avail. Even 296 gives prime errors after a few minutes. Although the number of minutes before errors seems to be going up so just maybe I can get it stable at this.

I'm using corsair 6400 DDR2, I suppose I need a different point for DDR2? Anyway I haven't tested too much yet but at 290 i'm stable whereas 299 gives errors when doing prime blend test, but not on cpu only test. So either my memory is not getting enough juice or the memory controller is the problem.

Did you upgraded your bios to version 1.8 ? It fix DDR2 issues and its very easy to do it in windows

Yeah I flashed 1.8 even before I got my DDR2, I'm pretty sure the chipset just can't handle it. I bought this board as a temporary board anyway, just waiting to see if the NF590 boards with C55 will be good otherwise I'll buy a board with intel chipset.

Hmm... it turns out i had memory compatibility option turned on all along. Which means my memeory was running at speeds way lower than FSB. Now I turned it of and while my FSB is running at 290, hwinfo32, which should report right says memory is running at 360. Clockgen and cpu-z don't give memspeeds at all anymore (where clockgen was right before and cpu-z gives wrong values anyway). It now seems even at 290 i'm not prime stable, I wonder if it's the chipset, the memory or the vdimm, since I think the board doesn't even give the voltage the mem is supposed to run on...

EDIT: it isn't even prime stable with everything on stock, wth?

[Mallet]

Hey what do you guys think, is 3.3Vdimm rediculous to try? Im using 2x512 kit of kingston value ram. I got heat spreaders on it. I am going to upgrade to ddr2 soon anyhow to get a 2gb kit but ddr2 prices have gone way up lately. Think i should give it a go, i have to use 333mhz setting past 308fsb.