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4850 oc vs 4870 oc

Greebo

Greebo

Greebo

Caporegime
Joined
20 Jan 2005
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Co Durham
Assuming 4870 aren't cherry picked, how much quicker will an overclcoked 4870 be over a 4850?

I know the 4870 has gddr5 memory and can overclock to at least 4400Mhz but how much difference does the gddr5 memory make?

The 4870 has a much higher core speed than a 4850 but the 4850 could in theory run at the same overclocked core speed as the 4870.

What I am getting at, if the 4850 and 4870 overclock to the same core speed, does the gddr5 add 5% or 10% or what difference?

If only 5-10% then if you intend to overclock your 4850 especially under water, it is never going to be worth the extra £60+ to buy the 4870?

Comments, suggestions, actually overclocking results welcome.
 
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good thread, i'm interested in this my self. I was all out for the 4870 but i'm not ruling out the 50
 
What's the rated speed of the memory on the 4870? You say it can clock to "at least 4400Mhz" as if they're all guaranteed to hit this speed. Is the 3.6Ghz memory clock below the rated speed of the chips? Do all cards use the same chips?
 
Defcon5 said:
Is the actual core the same then? Just one has GDDR5
and the other 4?
Click to expand...

AFAIK yes. Just from what I have read.

The 4870 comes with higher clocks from the start.

And vertigo, that was an example and I'm asking. Yes both 4850's and 4870's will vary in their acheivable overclocks just like all cards.

I was trying to make a point about the huge memory bandwidth which will be available be either 3600,4000 or 4400Mhz.
 
we need people to oc their 4870s and bench....there are lots of 4850 benches out there.


and I am pretty sure the 4870s are not speed binned because they use over .1V more than the 4850. In other words, they are just fed more voltage for the higher clock rate.
 
This Video card is equipped with GDDR-5 microcircuits from qimonda production with access time 0.5 ns, capable of working at 4 GHz DDR. Theoretically, this memory has certain overclock reserve.
Click to expand...

so I guess it has a little ehadroom, but maybe its underclocked and running a slightly lower Vdimm too as not many seem to have managed to push it very far.

In terms of actual difference, the 4870 is reportedly only 20-25% faster.
 
Umm here's an ATI tool test, although it appears it's not compatible with vista 64 until a driver has been digitally signed. :rolleyes: On XP you could overwrite that and install anyway but not any more it seems. (probably another way round it though)

ati-tool-bench.jpg
 
3Dmark06 is not worth running for a comparison.

If someone has a c2D that can manage 3.5ghz and a 4850, I can run a couple of benchmarks if we can agree on a list.

My system:
4GB DDR6400 @ Cas5, 5, 5, 15 etc (can drop to 2GB @ cas4)
C2D 8200 @ (anything upto 3.8, maybe 4 at a push of Vcore)
Saphire HD4870
Cats + Hotfix.
Vista32 bit

Only have COH thats DX10, but a few other titles.
 
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I still think 4870 will be still worth it due to higher bandwith and later 1GB memory versions.
4850 might not be up to it at very high resoultion and maxed details with AF/AA maxed.

Unless the money is the issue, but then still that's different story.
 
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