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4850 1gb vs 4870 512mb

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July 25, 2008 1:22:43 PM

As far as I've understood the only difference between the 4850 and the 4870 is that the 4850 has GDDR3 and the 4870 has GDDR5.

Would it therefore be reasonable to expect the 4850 1gb to preform similarly to the 4870 512mb on benchmarks?

has anyone seen benchmarks for the 4850 1gb?

More about : 4850 1gb 4870 512mb

July 25, 2008 1:38:16 PM

No, the amount memory difference will do not offers more bandwidth, where the GDDR5 excel.

The 1GB will help the 4850 to keep better framerate at higher resolution but the core is still lower clocked than the 4870.
July 25, 2008 1:38:21 PM

The memory is not the only difference. The 4870 has a higher clock speed 750mhz vs 625 mhz. I would only expect the 4850 to match the 4870 in ultra high resolutions that would allow 1gb of video ram to make a difference. Other than that the 4870 should normally beat the 4850.
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a b U Graphics card
July 25, 2008 1:51:16 PM

It would depend on what resolution you running, and how high you are running all the eye candy, and AA/AF.
Under most conditions, I would venture to say the 4870 is still a faster card.
Although I have not seen benchmarks from the 4800 series on this, it was proven on the 3800 and 8800 series that anything over 512 meg of memory on a single card was more of a marketing ploy than anything. In fact, in most benchmarks, 2 identical cards except 1 with 1 gig of memory and 1 with 512 meg of memory....the 512 meg version of the card 90% of the time was faster.

Running the 2 cards with 1 gig in Crossfire or SLI did show some improvement, as 2 cards together can run higher res, and higher settings all around and the extra memory did show it helped some, but not a significant amount over 2 -512meg cards.

It would be interesting to see if the new cards do indeed make better use of memory over 512 meg than the last series.
July 25, 2008 1:55:13 PM

512MB seems to be plenty for RV770 cards, even at high resolutions + AA & AF. How this holds out in future titles will be interesting to see, but for now 512MB HD4870 >> 1GB HD4850.

Oh yeah, Crossfire might benefit from more VRAM, but I haven't seen any real tests suggesting this aside from the preliminary HD4870X2 stuff.
July 25, 2008 4:00:37 PM

Anyone posting here read the anandtech article about the 4870x2 with 2 GB? They compared it, among other things, to 2 x 4870s (512 MB) in CF, and found that in certain scenarios it was still substantially faster.

Link: http://www.anandtech.com/video/showdoc.aspx?i=3354&p=7

Based on that, and on past comparisons of cards with 320, 512, 640, and 1024 MB video RAM, I disagree that extra RAM beyond 512 MB is non-beneficial, specifically with games that have complex textures on high resolutions with AA turned on.
July 25, 2008 4:20:15 PM

TeraMedia said:
Anyone posting here read the anandtech article about the 4870x2 with 2 GB? They compared it, among other things, to 2 x 4870s (512 MB) in CF, and found that in certain scenarios it was still substantially faster.

Yes and I found that very interesting. Two 4870s in Crossfire seem to be fast enough to make good use of the larger framebuffer, but we'll have to wait and see what it will do for *just* a single 4870 :lol: 
TeraMedia said:
Based on that, and on past comparisons of cards with 320, 512, 640, and 1024 MB video RAM, I disagree that extra RAM beyond 512 MB is non-beneficial, specifically with games that have complex textures on high resolutions with AA turned on.

That's not really a valid comparison, Radeons can do more with less as far as video RAM is concerned.
July 25, 2008 4:29:04 PM

I agree, the 4800's are very efficient with using video RAM.
July 28, 2008 7:30:24 AM

For clarification purposes don't both the 4850 and the 4870 have identical chips?

Yes they have different clock speeds (625Mhz vs 750mhz...thanks lesterf) and hence are not really comparable.

If we could increase the clock to 750mhz for the 4850 (with a proper cooling solution should be possible since it runs pretty high with stock cooling fan) would we get comparable benchmarks (the only difference being then the 1gb of GDDR3 vs 512mb of GDDR5) or does the GDDR5 make such a big difference in itself?
July 28, 2008 7:39:42 AM

The reason they have different clock speeds is for stability, it makes perfect sense, you pay more for chips capable of higher speeds.

As the chips come off the production line, the manufacturer will grade them into good chips and average chips (very simplistic example). The good chips go into the 4870s, they're stable at higher clocks, the average chips go into the 4850s, because they're unlikely to remain stable at the higher frequency.
July 28, 2008 11:38:55 AM

gulogulo96 said:
For clarification purposes don't both the 4850 and the 4870 have identical chips?

Yes they have different clock speeds (625Mhz vs 750mhz...thanks lesterf) and hence are not really comparable.

If we could increase the clock to 750mhz for the 4850 (with a proper cooling solution should be possible since it runs pretty high with stock cooling fan) would we get comparable benchmarks (the only difference being then the 1gb of GDDR3 vs 512mb of GDDR5) or does the GDDR5 make such a big difference in itself?

GDDR5 gives the 4870 a little less than twice the bandwidth of the 4850; it makes a big difference. Getting a 4850 to 750MHz could be difficult, but even if you could there is no way you could even get close to GDDR5 level memory bandwidth with GDDR3, so the 4870 will always hold a significant lead over any 4850.
October 1, 2008 5:32:00 PM

So even with just 256bits for memory, the GDDR5 makes it pretty close to GDDR3 with 512bits of memory? Can I assume that this comparison is valid?

If this is the case, it would be awsome to see a 384bit GDDR5 memory!
October 2, 2008 5:23:36 AM

ATI's new chips all seem very small in relation to Nvidia's and many of their older chips (2900 anyone?). I believe that you need a certain size die, perimeter exactly, to use a larger bus width. So if this keeps up, it doesn't look like ATI's cards will be using anything more than a 256-bit bus for awhile (if ever). Besides, there's no way the 256-bit bus at GDDR 5 speeds (which get faster than the 4870 uses) will be a bottleneck.
Anonymous
a b U Graphics card
September 11, 2010 7:07:26 AM

dude its date 11-892010 yesterday i bouht 4850 abour 6800R.S so resident evil 5 i test bence mark test is giv b & my prosser is amd phenom x2 550 & 2gb ram my other 2gb ram is in service center so i will know real perfomence after bring 2gb ram so 4850 i think best performance & 4870 is not available in market
September 12, 2010 5:26:09 PM

Two xfx hd4850 1gb 256 bit gddr3 dx 10.1 at full pci-e 16x 2.0 each lane. w.e.i 7.3 stock! And i am happy with it.
a c 271 U Graphics card
September 12, 2010 5:56:49 PM

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