Vddq & Vref...worth it on the 9800Pro

[Hell-Fire]

I am doing the Vgpu and Vddr on my 9800Pro, and figured while I had it out and modding away..would think about doing the other 2 mods.

Is it worth it to do these mods?

[bachus_anonym]

i did vgpu and vddr mods and my R9800P and got this weird prob with not being able to clock my mem as high as before the vgpu mod... before 430/385 no prob... now 460 on the core (1.74v) but 350mem (no matter what voltage) to get it artifacts-free...

i'm just waiting for 20k and 50k trimmers to arrive (next week probably) and complete this thing with with vddq and vref mods... there's probably nothing else i could try...

give it a go and maybe tell what results u get...


P.S. I was thinking... if 10K maxed out trimmers give me 1.74v vagp (1.71v default) and 3.44v vddr (3.35v!!! default) after plugin-in the mod would using 20k trimemrs help me start with default voltages on both mods and then, say, leave vgpu at 1.71 and crank up vddr with no artifacts? just a thought...

[andyddr]

bachus_anonym had the same problem here. Flashed to the Gigacube BIOS and now all better. Can get 450Core and 400Mem no artifacts and no mods. Will mod Vcore and Mem this weekend permantly though and most results.

[Stang_Man]

i did the vddq, and it didnt' help at all. instead of using a 50k VR, i would recommend a 100K or 200K instead. i think it did more damage than good. :(

[bachus_anonym]

Originally posted by Stang_Man
i did the vddq, and it didnt' help at all. instead of using a 50k VR, i would recommend a 100K or 200K instead. i think it did more damage than good. :(

funny thing... i went over ocfaq guide again and noticed something that might help, at least in my case...
for some reason i always thought that vref should be 1/2 vddq (coz on my board w/o mods vref is 1.395v and vddq is 2.80v) ... and in fact is says that its 1/2 the vddr...
by board was at default vddr of 3.35v (after mod 3.44v)... so it looks that i would need to raise vref to 1.77v to get this working properly... can't wait for those trimmers now...

[Hell-Fire]

Let us know how it works out as I am curious about this as well.

[bachus_anonym]

hehe... unfortunately, life has vapourised out of it.... R.I.P :(

[Hell-Fire]

9800Pro fall down go boom.

Well, they are selling them at CompUsa for $199 right now.

[bachus_anonym]

$230 after instant rebate and additional $30 mail-in....

hmm... i guess i'll pick one up tommorow on the way to work :-) :banana:

thanx bro,

[Deathangel]

I am very interested in this also, I didn't see this thread before I posted a different one. I was looking through the data sheet on the Samsung chips which is what mine has and found this note in operating frequency

1. Under all conditions VDDQ must be less than or equal to VDD.
2. VREF is expected to equal 0.50*VDDQ of the transmitting device and to track variations in the DC level of the same. Peak to
peak noise on the VREF may not exceed + 2% of the DC value.
3. Vtt of the transmitting device must track VREF of the receiving device.
4. VIH(max.)= VDDQ +1.5V for a pulse width and it can not be greater than 1/3 of the cycle rate.
5. VIL(mim.)= -1.5V for a pulse width and it can not be greater than 1/3 of the cycle rate.
6. For any pin under test input of 0V < VIN < VDD is acceptable. For all other pins that are not under test VIN=0V.
7. For K4D26323RA-GC2A/33/36, VDD/VDDQ=2.8V + 5%

It seems that raising Vref and Vddq could have a good chance of raising overclocks or at least stability as far as artifacting (possibly from not enough Vddq and of course you would have to raise vref to .50 as in the data sheet it is said that it is expected to be .50 of vddq. I need to get some bigger trimmers or try maybe a 100k fixed and see what i get, then move down accordingly.
If you look at the chart on the data sheet it says that absolute maximum is 3.6v :slobber: for the chips but they are not recommended to run for comtinuous time over ref voltage of 2.8 and max of 2.94.

[Hell-Fire]

Just for anyone looking at this, the DCC Value listed in #2 does not stand for Direct Current ie: voltage. DC Value is the average value of a voltage waveform. These are 2 vary different things.

Thats some interesting information.

[Deathangel]

Well, I broke down and did the vref and the vddq but I did not get too much of a raise with a 50k resistor. I wanna try a 100k but I am not too sure of the outcome, voltage wise, if I jump to a 100k. Theoretically it would be double of what I have fron the 50k but I am not too sure on that. Right now with a 50k on both Vddq=2.741 and Vref=1.420. I'm not real sure about the limits of these but I dont think going to 1.440 and 2.880 would kill it but I dont know. I don't want to risk my card of death but I wonder what 100k would give me or if it would fry the card. I got about 10mhz from 360 to 370 so an effective change of 20mhz on the memory. I got some pics but I will have to upload them and then I will post them.

[Deathangel]

Here's a couple pics,


http://miteymouse22.home.insightbb.com/Images/9800back.gif

http://miteymouse22.home.insightbb.com/Images/9800side.gif

[Hell-Fire]

Those Radio Shack sinks are getting real popular.

Looks like a nice and tidy mod. Well done.

I use those molex plugs for most of my volt monitoring as well.

I see you went with a fixed resistor.

[Deathangel]

Yay, fixed one for now, but tomorrow I think I am gonna run up to radioshack and get a 100k VR and see if I cant raise it up some more and see what I get. I'll report back after I do it tomorrow and see if I dont get a more moderate raise in memory clock. Them radioshack sinks arent too bad, I didn't feel like ordering a set online and these were right up the street when I needed them. They seem to cool rather well.