ATI 4850/4870 voltmod thread

[SetteUltras]

So around 1.3v it is. Good to know. Thank you guys both

[cowie]

i found that the sweet spot on my 4850 is 1.32 to the core,good for 865 in all my benchmark games and still runs cool e-nuff for 24/7 use on my as1 for cooling.
as a matter of factly it seems that it does not scale well with volts after 1.35,max clocks at 1.40v only modest increase to 885 from 1.32v 865.
even with temps 27c ilde 45c load

[rangerone7669]

Order a different one.

I also suggest a 5 ohm fixed resistor in series to keep from creating a dead short.

ok ty, i wasnt sure. thats why i asked. i've only done a few volt mods in the past.

i dont really understand most of what i'm doing with electrical componets, but i'm good at following directions. everyone i've tried so far have worked.

i did flash the bios on my 4870 with better fan speed, and increased the 3d voltage, but i dont think it worked. 830 on the core is still my max stable.

[SetteUltras]

i found that the sweet spot on my 4850 is 1.32 to the core,good for 865 in all my benchmark games and still runs cool e-nuff for 24/7 use on my as1 for cooling.
as a matter of factly it seems that it does not scale well with volts after 1.35,max clocks at 1.40v only modest increase to 885 from 1.32v 865.
even with temps 27c ilde 45c load

It seems the core has no problem surviving at 1.3-1.4v.
The thing is whether or not the rest circuit (vrms etc.) of 4850 can handle such high voltage in the long run...

[adpr_02]

So there is a sweet spot for vMEM as well:

At EXACTLY 1.075v I am rock stable at 1200mhz. Any higher or lower, and I cannot be stable. So the ram is capable, you just have to find the right voltage. Stability is checked by 1 hour Furmark, 6 loops of crysis benchmar, then 3 loops of 3dmark06. If no artifacts, I'm stable.

Also, it gets really hot at 1200mhz. I have some beefy heatsinks on it, and they still get pretty hot.

[Jamesrt2004]

Just a bit of info about power requirements and so on. I've asked Steve on legionhardware.com to check power consumtion of OCed system if possible, and he gave some extra info over here.

System is Q6600 @ 3.0 GHz with HD4870+Accelero S1. Rest of system is pretty normal (500GB disk, 2GB memory, X48 chipset). Stock temps are 74 idle, 82 load (stock clock/cooler) under Crysis.
Power consumption was 193W/295W and on 830MHz core/1150MHz memory (with S1) it got up to only 202W/303W (idle/load). You can see more data (temps, consumption, 790/1100MHz OC which is top with CCC, etc) in third post.
830/1150 was max oc with this setup.

Since you people say rising voltage on 4850 would result in much higher power (400+W) on around same OC (800+ MHz) I guess paying extra $$ for 4870 is better than paying extra for 4850+new PSU and than still having to bother with voltmoding and the rest.

And 303W total power should be more than acceptable to my 450W PSU even if it had lousy 75% efficiency. And I still have just dualcore vs quad (which is used in review)

Thanks for advices everyone, and I hope this info will help others as well!

my system is roughly about the same as yours, well not much different n I had a FSP 550w 85% psu n that couldn't handle it so be wary mate

[zbomb5610]

So there is a sweet spot for vMEM as well:

At EXACTLY 1.075v I am rock stable at 1200mhz. Any higher or lower, and I cannot be stable. So the ram is capable, you just have to find the right voltage. Stability is checked by 1 hour Furmark, 6 loops of crysis benchmar, then 3 loops of 3dmark06. If no artifacts, I'm stable.

Also, it gets really hot at 1200mhz. I have some beefy heatsinks on it, and they still get pretty hot.

i agree on the memory having a sweet spot, mine was at 2.07v as well, i can do 1225 and i don't get any artifacts in the benches i run.

[keninishna]

I've find the measure point and correct the photo

Yes thank you I was reading 12 volts also I was thinking my multimeter was bad for a little while.

[adpr_02]

Yup. Just tried 1225 for the first time and it works great. Real glad about it. Time to try 1250... who knows, it might work.

[Big.Wayne]

So i just got back from radioshack. Only to find out that my Multimeter needs a batter which i don't have

and to find that the soldering iron i got doesn't get hot enough to melt the solder on the boards.

AND to find that my solder fell out of a hole in the bag when i was walking home... this is a great day

That made me chuckle wesleyclark!

How are you getting on with the HD4850 moddin now?

I've bought myself a MM but at this point have no idea how to use it, however mine did come with a battery . . . I'm on a roll!

P.S I love these XS animated icons

[W1zzard]

vddc reading spot fixed, the picture in the article now points to the correct location

[LuxZg]

my system is roughly about the same as yours, well not much different n I had a FSP 550w 85% psu n that couldn't handle it so be wary mate

Argh! Well, guess I'll just have to try it anyway, the hell with it!
Btw, could you give me some more info in what way it couldn't handle it? Didn't run at all, was crashing, or you just couldn't OC it?
As right now, I'm just looking at it WORKING out of the box with this PSU and CPU .. even if I'll have to lower CPU clock a bit (or a lot)

Tnx for the info anyway

[babalouj]

What resistance should I be shooting for across the resistors for the 4870 MVDDC and MVDDQ pencil mods?

[rym]

Is there a nother spot to solder to ??. the pad pulled off.

[SNiiPE_DoGG]

Is there a nother spot to solder to ??. the pad pulled off.

you can still solder to that point... it just takes some extra steady hands. No you cannot solder to the other one you pointed to, as you can clearly see it is on a different microtrace

[rym]

solder wont adhere to it since the spot is greatly reduced to solder to. from a grain of sand size now to a pin piont.

[diablos]

vddc reading spot fixed, the picture in the article now points to the correct location

It is wrong again, look at this
http://www.xtremesystems.org/forums/...&postcount=524

[W1zzard]

thats basically the same spot, mine is just easier to reach imo

[SNiiPE_DoGG]

solder wont adhere to it since the spot is greatly reduced to solder to. from a grain of sand size now to a pin piont.

you need to scrape or use a solder sucker dealy to remove the flux that is on the board, there is a ton there i can see in the pic, flux wont let solder ever stick there

[binormalkilla]

So I'm reading up on volt modding in preparation for my 4850s' arrival. Are there any good reading sources for guides, etc.? I've read the VR Zone review here.
I'm still reading through this thread (LOL it's long), but I would like to know where the measuring points for the DMM are. I plan on finding the max OC on stock voltage with WC, diting the BIOS with RBE (I'm familiar with this...) and finding the max OC, then performing the pencil mod and finding the mac OC....

I have a cheap little soldering iron and a radio shack multimeter, but I'm not comfortable enough with the soldering iron to solder such small components without more practice.......however the radio shack DMM should suffice.

[DemonEyez]

I was wondering. I did the vmem mod for the HD4850 with a 100K VR. The lowest voltage I can get is 2.10v , without the mod it's 2.04v After reading that there seems to be a sweet spot at 2.075v i want to redo the mod so i can get a lower voltage. Should I replace the 100K VR with a 50K VR?

[eddieobscurant]

I have the same question/problem with DemonEyez. We need 50K VR or 200K VR to achieve what we want? I think 200K VR , right?

[r4st4m4n]

So I'm reading up on volt modding in preparation for my 4850s' arrival. Are there any good reading sources for guides, etc.? I've read the VR Zone review here.
I'm still reading through this thread (LOL it's long), but I would like to know where the measuring points for the DMM are. I plan on finding the max OC on stock voltage with WC, diting the BIOS with RBE (I'm familiar with this...) and finding the max OC, then performing the pencil mod and finding the mac OC....

I have a cheap little soldering iron and a radio shack multimeter, but I'm not comfortable enough with the soldering iron to solder such small components without more practice.......however the radio shack DMM should suffice.

If you haven't read this, you should : http://www.xtremesystems.org/forums/...d.php?t=115387

[babalouj]

I was wondering. I did the vmem mod for the HD4850 with a 100K VR. The lowest voltage I can get is 2.10v , without the mod it's 2.04v After reading that there seems to be a sweet spot at 2.075v i want to redo the mod so i can get a lower voltage. Should I replace the 100K VR with a 50K VR?

You will need more resistance aka 150K to 200K ohm VR.

[Jamesrt2004]

Argh! Well, guess I'll just have to try it anyway, the hell with it!
Btw, could you give me some more info in what way it couldn't handle it? Didn't run at all, was crashing, or you just couldn't OC it?
As right now, I'm just looking at it WORKING out of the box with this PSU and CPU .. even if I'll have to lower CPU clock a bit (or a lot)

Tnx for the info anyway

Under load in a few games it would just Restart that was all sometimes would do it sometimes wouldn't was kind of random but new psu = solved everything