ATI 4850/4870 voltmod thread

[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.

[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

[W1zzard]

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

[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.

[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

[binormalkilla]

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

I've seen that here, but I'm at work and it seems our routers are blocking something, as I see nothing in that first thread.....I'll check it out when I get home.

[dean0]

iam going to pick up some 10ohm resistors tommorrow for 4870vgpu mod, but im not to sure which one i need, this is what they sell;
http://www.maplin.co.uk/Module.aspx?...C=SO&U=strat15
What increase in voltage will this achieve? thanks in advance

[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?

[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.

[DemonEyez]

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

Thanx for the info! Will pickup a new 200K trimmer this week. Crysis gives me artefacts at 1200MHz and 2.12v.
really want to try less voltage :P

[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?

[alexio]

Will a 100 Ohm vRES do for the HD4870 vGPU mod? It's a 15 turn so I reckoned it should be fine.

[SNiiPE_DoGG]

Will a 100 Ohm vRES do for the HD4870 vGPU mod? It's a 15 turn so I reckoned it should be fine.

but of course sounds good to me, some people have suggested soldering a 10 ohm fixed into the line before the pot to prevent any accident that may occur, i used 3 fixed 10ohm in series for mine because i prefer low matinence

[rym]

if you have a stock 4850 heatsink thats intact i want it..

Randy

[JamesBong420]

rym i have a spair 4850 sink..

also i could not resist i grabbed a 4870 as well. $274... so now i need to find a nice 2x16x pcie mobo all i have is 16x 4x.

http://www.tigerdirect.com/applicati...1&sku=D10-4870

[Laykun]

rym i have a spair 4850 sink..

also i could not resist i grabbed a 4870 as well. $274... so now i need to find a nice 2x16x pcie mobo all i have is 16x 4x.

http://www.tigerdirect.com/applicati...1&sku=D10-4870

Arg, I did the same thing. I went out and grabbed an X48 motherboard, and the difference it makes in phenomenal.

[overcrash]

I have a volt mod on my 4870, but I have a strange problem. I can bench on 850/800, and on 650/1150, but when I clock both the memory and core, the max I am stable is 800/940. VDDC is 1.307v idle and 1.363v load. I think it's OCP ( over-current protection ), but I'm not certain that is the case.

[aussie-revhead]

I have a volt mod on my 4870, but I have a strange problem. I can bench on 850/800, and on 650/1150, but when I clock both the memory and core, the max I am stable is 800/940. VDDC is 1.307v idle and 1.363v load.

Why does the 4850 clock so much better than a 4870 ? Are very high clocks achievable in CF too ? I have seen mention of 1ghz on the core , wouldnt two of those crush a pair of 4870's (790/9xx) ?

[alexio]

Why does the 4850 clock so much better than a 4870 ? Are very high clocks achievable in CF too ? I have seen mention of 1ghz on the core , wouldnt two of those crush a pair of 4870's (790/9xx) ?

2x HD4850 is much more powerful than 1x HD4870, but the 4850s in a pair cost a bit more. HD4850s aren't actually better than HD4870s for overclocking though. I've yet to test my second card but the first one does 870/1235 Furmark stable, so it should do mosts benches at 900MHz core. Everything is stock, but the fan runs at 100%. I haven't seen an HD4850 that benches at 900MHz with only 1.265v vGPU (stock 4870 vGPU). I'm not even talking about the DDR4940 memory The RAM needs more volts though because the card performs equal or worse above DDR4700 than it does at DDR4700.

[aussie-revhead]

OK cool , do we have software yet that can clock these cards this high with CF enabled ? What are you guys using to clock so high ? (ie CCC only goes to 790 and the evga tool didnt support two clocked cards last time I tried).

Is there a pencil mod for 4870 ? Or solder mods only ?

[keninishna]

I have a volt mod on my 4870, but I have a strange problem. I can bench on 850/800, and on 650/1150, but when I clock both the memory and core, the max I am stable is 800/940. VDDC is 1.307v idle and 1.363v load. I think it's OCP ( over-current protection ), but I'm not certain that is the case.

I'm having the same issue my memory goes up to 1200 with core at 750 but I can get my core up to 880 with memory at 750. but something like 860/1000 is completely unstable. I'm trying to do the memory volt mod to see if I can get some sort of stability but I'm not sure about the memory voltage reading for vddc I read 1.5 volts. I have 1.47 volts on the core now. Its wierd though I can get 880 core and 1150 memory artifact free in ati tool but drivers crash in 3dmark

[G H Z]

First mod on this new card, fan now runs 100% from POST to shut-down, perfect for air benching. Now 3DMark06 stable on default VGPU @ 875/1175 (AMD GPU Clock Tool) & 900/1200 3DMark01. I plan to do some BIOS overclocking this weekend, I'll keep you posted on the results.