Anyone here volt-mod their 4850?

[Modular]

Just got the latest issue of CPU and there's an article in there on 4850 volt-modding. I never thought I'd be the volt-modding type, but these cards are so cheap that if it were to go belly-up, I'd only be out about $120. Plus, I think it would be wicked to have 800+ clocks on the core

I just started reading on some other forums, but since this is my main tech forum, I thought I'd ask around here for advice and experiences.

 

[speedfreak]

before doing that be sure you slap a good aftermarket cooler on that.

 

[bunnyfubbles]

well he does have an accelero s1 on it, so as long as he's got a fan to supplement, he should be fine

 

[Modular]

Thought I'd chime in with an update. The volt-mod went very well; I used a pencil to increase voltage from 1.08 (stock) to 1.25. I am currently at 750Mhz on the core (stock is 625) and can run Furmark and ATI Tool artifact checker for hours with no problems. I had it at 775mhz for about an hour with no problems but it errors if it runs much more than that.

I log everything with Rivatuner and my temps have never gone above 52C even after a few hours of COD: W@W or Crysis (tried both Warhead and Vanilla). No issues with Fallout 3 either. The S1 has a 120mm fan strapped to it, so I'm sure that's helping things quite a bit. The one thing I did notice was that at this higher core speed, my memory is about 5C warmer than it was before the mod but it's still topping out at 60C, so I'm not worried about it at all.

I'm definitely CPU limited at this point and am getting ready to drop in an X4 920 in a month or so and then the hunt for 800+ is on! I see no reason why I can't get this to 1.3/1.35v on the core with the cooling that I have. I left the memory voltage at stock as I really see no reason to mess with it as much. Also, from what I've read, memory can be very easy to kill with voltage, so I figure I'll get it to what it can handle at stock and leave it at that.

 

[firewolfsm]

I hope you know that the 4850 is almost completely memory limited. Without overclocking your VRAM that great core overclock will just produce heat and kill your card faster.

 

[Modular]

Originally posted by: firewolfsm
I hope you know that the 4850 is almost completely memory limited. Without overclocking your VRAM that great core overclock will just produce heat and kill your card faster.

I did not know that. Well, I knew about the heat issue, but honestly, 52C at the hottest is 50C lower than I was hitting with the stock cooler at stock voltages/clocks.

I have the memory at 1050 right now; I guess I'll have to mess with it more when I get the X4 in here to see what these overclocks are really netting me in performance.

 

[error8]

Originally posted by: firewolfsm
I hope you know that the 4850 is almost completely memory limited. Without overclocking your VRAM that great core overclock will just produce heat and kill your card faster.

It's not that memory limited as you think it is. 63.6 Gb/s is a lot of space for a fast core. Of course that it might hold the card back in some situations, but it's not like there is little to no improvement going from 625 mhz to 750 mhz. In my opinion, a 4850 at 750 mhz comes very close to a 4870.

 

[mwmorph]

Originally posted by: error8

Originally posted by: firewolfsm
I hope you know that the 4850 is almost completely memory limited. Without overclocking your VRAM that great core overclock will just produce heat and kill your card faster.

It's not that memory limited as you think it is. 63.6 Gb/s is a lot of space for a fast core. Of course that it might hold the card back in some situations, but it's not like there is little to no improvement going from 625 mhz to 750 mhz. In my opinion, a 4850 at 750 mhz comes very close to a 4870.

It is when compared to the 115.2GiB/s of a stock HD4870, 111.9 of the GTX260 and 141.7 of the GTX280.

Core voltage mods will help definitely squeeze out a few more %, but upping the memory cock i think would provide even bigger gains.

 

[bunnyfubbles]

Originally posted by: mwmorph

Originally posted by: error8

Originally posted by: firewolfsm
I hope you know that the 4850 is almost completely memory limited. Without overclocking your VRAM that great core overclock will just produce heat and kill your card faster.

It's not that memory limited as you think it is. 63.6 Gb/s is a lot of space for a fast core. Of course that it might hold the card back in some situations, but it's not like there is little to no improvement going from 625 mhz to 750 mhz. In my opinion, a 4850 at 750 mhz comes very close to a 4870.

It is when compared to the 115.2GiB/s of a stock HD4870, 111.9 of the GTX260 and 141.7 of the GTX280.

Core voltage mods will help definitely squeeze out a few more %, but upping the memory cock i think would provide even bigger gains.

the RV770 really is pretty damn memory efficient, increasing the core will certainly help more than the memory, and I would think memory capacity (assuming he has a 512MB model) will be the major limiting factor even before memory bandwidth as long as he isn't running any higher than 1680x1050.

I would still agree with a stance warning against pushing the core much higher than 750MHz, the gains just wouldn't be worth it.

 

[Modular]

It is the 512mb model and I'm also on a 20.1" monitor, so 1680x1050 is my max.

 

[bunnyfubbles]

anyways :beer: cheers on the successful mod

might as well upgrade your memory the same time you upgrade that CPU (or even sooner seeing as how DDR2 is so damn cheep these days)

 

[kmmatney]

Can you up the Voltage with a BIOS editor, or do you have to mod it? I just used a simple BIOS editor for my old 2900Pro, which worked perfectly. (My HD4830 seems to overclock well without any mods, so I haven't looked into editing the BIOS)...

 

[Modular]

Originally posted by: kmmatney
Can you up the Voltage with a BIOS editor, or do you have to mod it? I just used a simple BIOS editor for my old 2900Pro, which worked perfectly. (My HD4830 seems to overclock well without any mods, so I haven't looked into editing the BIOS)...

You can, but only up to 1.2 volts. That's probably enough to get the clocks I'm at, but I'm not sure. I wouldn't have done this mod at all if my card would have put up a decent overclock stock, but it wouldn't. It maxed out at 675mhz stable, whereas most people are getting 700mhz easy. The reason is that my stock voltage was so low. I was at 1.08-1.09 stock, but the card should be at 1.15.