4850 OC's seem funky

S

superkdogg

Gawd
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Oct 14, 2004
Messages
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So, since the 4870 and the 4850 have the same GPU but running different clockspeeds, wouldn't one expect the 50 to OC at least to the level of the 70?

I wonder what's holding down the OC's so much. My first thought was that the 4850 was an awesome card and an OC'ers dream, but then two sites I found (here being one) had only ok overclocks with it and the memory is really going to hold it back (purely from an OC perspective), not that it's not a good card at stock-I just had hoped more based on the previews.

First one to put a big cooler on it and Vmod wins!:D
 
First, the 4850 is GDDR3 instead of GDDR5 like the 4870. Second, you have a point! It could be like the 2900Pro vs 2900XT. Most Pros were able to be flashed to the XT. I guess after the bios/driver fixes come out, we will find out.
 
superkdogg said:
I wonder what's holding down the OC's so much.
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The heatsink is the limiting factor for the GPU overclock, most likely. The 4850s have a piddly little copper heatsink while the 4870s have a huge dual-slot cooler that exhausts out the back. Paired with a good aftermarket cooler, I'd expect the 4850s to be able to hit fairly close to 4870 speeds. They are binned lower though, so it's possible that they just aren't capable of the higher speeds. Given the impressive yields of RV770 so far however, there's a good chance the 4850s will really open up with better cooling.
 
overclocks are being held back by the lack of overclocking tools. all we have available is overdrive in the control panel. that limits us to 700mhz core.
 
Even the 700 mhz is higher than what I've read so far, so that's encouraging.

Regarding temps, they seem to be 'ok' comparatively at stock speeds but those coolers do look like they don't have much headroom for keeping it cool running over spec.

I doubt a bios flash will be possible here because the GDDR3 and GDDR5 probably require too many differences. If there is a custom bios that supports flashing just the GPU function without bricking the card I'll be impressed.

Does AMD 'bin' their cards actively, or do they just whip out as many GPU's as they can? I'm asking because I don't know, but it's long been said that CPU's are binned and usually they are just assigned a stock clockspeed that has no real correlation to oc in many cases (not all, many). It seems to me that AMD is probably just mass producing both cards and slapping one GPU on each card, since both cards dropped at the same time so it's not like they had time to refine the manufacture process or anything yet. I could be wrong, just trying to use logic....
 
superkdogg said:
Does AMD 'bin' their cards actively, or do they just whip out as many GPU's as they can? I'm asking because I don't know, but it's long been said that CPU's are binned and usually they are just assigned a stock clockspeed that has no real correlation to oc in many cases (not all, many). It seems to me that AMD is probably just mass producing both cards and slapping one GPU on each card, since both cards dropped at the same time so it's not like they had time to refine the manufacture process or anything yet. I could be wrong, just trying to use logic....
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All manufacturers with multiple product tiers bin their processors. That's just how it works. Otherwise, they have no way of knowing whether any single GPU will work at a certain clock speed. Also, ATI has had a long time to refine their manufacturing process, since they're using the same one that they used for the HD3xxx line.
 
Voltage and lack of tools. 700mhz barrier has been broken, but needs a pencil mod and some RBE editing. Hopefully, we'll get a software solution soon ( ie ATItool ) and a pencil mod will suffice for decent clocks after some cooling.
 
SilverSliver said:
Voltage and lack of tools. 700mhz barrier has been broken, but needs a pencil mod and some RBE editing. Hopefully, we'll get a software solution soon ( ie ATItool ) and a pencil mod will suffice for decent clocks after some cooling.
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That's kinda what I figured. Sounds good to me! I'm a fan of the pencil mod since s462, so maybe I will pick up one or a couple of those 4850's soon. I'm sure ATI Tool is on the case, and RT/etc. are right behind for support.
 
I have a feeling that overclocking support in third-party apps will be arriving very soon, since the RV770 is fairly similar to the RV670. When that happens, we should have a better idea of its limits.
 
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