ATI 4850/4870 voltmod thread

[I34z1k]

Hey guys

What's MVDDQ and MVDDC? How do they affect stability? Saw them on W1zzards awesome vMod page

Thanks

900/1175 and counting

[Astennu]

Ive done the pencil mod on my 4850 but over 1.35v im getting random reboots when running Fur bench even as low as 700 on the core. im running a 850w Silverstone Zeus, do you think this extra voltage is pulling too much ? i dont want to buy another psu and find its the same. Is the sinlge 6pin on the 4850's enough ?


btw card is water cooled, never going above 45c and i have heatsink on the VRM's and according to GPU-z the dont go over 45c with a fan blowing on them.



*EDIT*




both my cards do the same as yours, what temps does GPU-Z report for your vrm's ?

I would say try the hard mod. Maybe the connection you made is not stable enough so the voltages are fluctuating.

Hey guys

What's MVDDQ and MVDDC? How do they affect stability? Saw them on W1zzards awesome vMod page

Thanks

900/1175 and counting

You are talking about a HD4870 right ?

[aussie-revhead]

HD 4870 voltmod article posted: http://www.techpowerup.com/articles/...g/voltmods/153

would be really cool if there would be a volunteer to add more text to these articles for less experienced readers

Good stuff mate but where are the results ? How do you get past the ccc gpu ceiling (without bios flash)?

[I34z1k]

Yep.

@ Aussie, use AMD GPU tool

[LuxZg]

Well if you have a good psu and the PCI connector is on a rail that can handle it its no problem. Those 3 12v wires can handle the wattage only the PSU should be able to do it. The pci 1.0 specification is rated 75 watt for the connector. So a 1.0 certified connector should at least be able to handle 75 watt. But new psu's can easily do more.

The HD4870 is pulling about 40 watt more then a HD4850. A HD4850 on 1.23v 776-1125 is pulling 5 watt more then a HD4870 on 790-1100. The HD4870 is running 1.28v.

If you go from 1.19v to 1.23v on the HD4850 you get + 25 watt. So you can make a indication of how much 1.45v will use on the HD4850.

Thanks, seems that 4870 is more power efficient, and I see it running on 278W (whole system with quad cpu, non-oced) so I should be fine with it on stock clocks or moderate overclock, which is still good for my PSU while 4850 OCed to same speed would obviously be overkill Tnx for helping!

[aussie-revhead]

Yep.

@ Aussie, use AMD GPU tool

Thank you , I have a pair of 4870's coming tomorrow and I want to get everything I can out of them.

[adpr_02]

hey dude, what did you use to stick those sinks on there?

Epoxy. It's my first time ever using it on a computer component and it works like a dream. Removing the sinks is basically just twisting them off - reall nice stuff. I might have to ditch my AS5

[Protagoras]

Hey guys

What's MVDDQ and MVDDC? How do they affect stability? Saw them on W1zzards awesome vMod page

Thanks

900/1175 and counting

According to Qimonda's data sheet, MVDDC is the device supply voltage(gddr 5 data sheet)/ power supply voltage (gddr 3 device sheet), and the MVDDQ is output supply voltage(gddr 5 data sheet)/ power supply voltage to i/o buffer (gddr 3 data sheet).
I am quoting the gddr 3 sheet because it seems to explain what MVDDQ is more clearly compared with the gddr 5 sheet - however, Qimonda might have changed terminology with gddr 5, so don't trust the gddr 3 definition blindly.

Now, regarding voltages for MVDDQ and MVDDC - I dont have my card yet, so I dont know the actual card voltages, but guestimating with the gddr 5 data sheet in mind suggests maximum operating voltage for both MVDDC and MVDDQ at 2.0 volts, and the operation max voltage at 1.545 volts. However, since the gddr 3 recommended max operation voltage is 1.9, and that we have seen 2.1 volts for MVDDC for the gddr 3 on the 4850 (a ~10% increase) I would guess that the gddr 5 could be run at ~1.7 without adversely affecting product life and stability. Then again, this is only a guess and should be taken with a grain of salt.

cheers,
Protagoras

edit: seems like the voltage specs are the same for both MVDDC and MVDDQ, so I would get them both to the same voltage.

[DemonEyez]

So shouldn't there be a mod for MVDDQ on the HD4850 also?

[Protagoras]

So shouldn't there be a mod for MVDDQ on the HD4850 also?

well... quoting form the data sheet, "GDDR5 SGRAMs are designed to tolerate PCB designs with separate VDDQ and VDD power regulators." However, this suggests that GDDR3 might not have this design feature, and its only available on GDDR5 memory. i.e, MVDDQ and MVDDC are the same/controlled by the same controller on GDDR3 boards, like the 4850, while the 4870 and future GDDR5 boards will have split controllers for MVDDC and MVDDQ. However, why they would split the two is beyond my knowledge... perhaps its there to add better voltage regulation, as "AC noise in the system is estimated at 50mV peak-to-peak for the purpose of DRAM[GDDR5] design" - which would mean that higher peak to peak noise to adversely affect the module's function.

edit: added more info

[DemonEyez]

Didn't have the X1900 en X1950 series also have separate MVDDQ and MVDDC? And those card also used GDDR3
If I remember correctly you could mess with those two in Atitool.

[Atzenkeeper500]

Hello together, can someone confirm/have tested the new pencil mod for the 4870? They post it on techpowerup: http://forums.techpowerup.com/showth...017#post876017

I am not in that soldiering, but pencil is ok. I pencil modded my evga 780i maiboard.
Thanks for an info

[BeastNotro]

W1zzard.. Posts here as well and he is the one who posted that techpowerup Voltage info and knowing W1zzard he tested it out before doing so.

[jason4207]

Hello together, can someone confirm/have tested the new pencil mod for the 4870? They post it on techpowerup: http://forums.techpowerup.com/showth...017#post876017

I am not in that soldiering, but pencil is ok. I pencil modded my evga 780i maiboard.
Thanks for an info

Pencil mod is only for the memory. vGPU mod is solder-only.

A pencil VDDC mod is not available at this time.

[aldamon]

Didn't have the X1900 en X1950 series also have separate MVDDQ and MVDDC? And those card also used GDDR3
If I remember correctly you could mess with those two in Atitool.

Yup, IIRC.

[Protagoras]

Yup, IIRC.

yup you are correct. I just checked and it seems that the r580 used the same or at least a similar digital voltage regulation to the one found on the 4870. From what I can on the board itself, it seems that the voltage regulation part for the memory is composed from two Pulse pa0511.221nl modules and two other chips, which I guess are vt200 series modules - I would guess that one set of vt200+pulse deals with the vddc and the other with the vddq. since I didn't really understand it at first, I researched how the memory access works with the gddr modules, and it seems that memory works by doing a column search followed by a row search in order to find the right bit - i.e find the data stored in the memory, which is then transfered to the buffer and from it to the lane to the gpu/cpu/ect. (I know, its a pretty bad explanation, but thats the best I got).
anyhow, so I assume that the vddc is "in charge" of the column search (CAS) and the row search (RAS) while the vddq is "in charge" of the buffer output.
Though I havent got the slightest clue why they would have two different power regulations for vddc and vddq

[Zucker2k]

Is the new AMD GPU tool with support for 4800 series cards out yet?

[Devious]

Is the new AMD GPU tool with support for 4800 series cards out yet?

Yes, version 0.9.8

I cant get it working with crossfire though.

[Sectorz]

Can someone help me please , I have drop the 1.865 ohm resistance to 1.644, but how I can know the voltage now ?And for the memory , I have a 3.9 ohm resistance , I need to drop it at how much for 2.15V ? thx for help in advance .

[SNiiPE_DoGG]

Here is my voltmod for the 4870, please tell me if you see anything wrong , I haven't been able to try it for myself yet because the 2nd card isnt here yet and i need to set up the water loop all at once

I used 3 x 10 Ohm metal film resistors in series. Note to any other first time volt modders like myself, that vddc point is a to solder to so make sure you are very practiced before you go for it.

[diablos]

is a 47ohm trimmer ok?

[W1zzard]

yes 47 ohm is great

[aussie-revhead]

Is the new AMD GPU tool with support for 4800 series cards out yet?

I downloaded a gpu tool but as above it doesnt support my 4870's. Does that mean Im stuck at CCC's 790 ceiling for now ?

I found the new one but as mentioned it doesnt seem to like CF .

Why does my 3D06 score go backwards when I clock to 790mhz ?

[LuxZg]

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!

[rym]

Is there a different solder spot fro the 4870 gpu v mod ?
see I killed the trace shown here in the pic. The little dot on the right side.

I see the same trace on the gpu side I could use but I would have to remove the cooler..
pain in the butt.