When we first heard about the overclocking potential of the 4890 from AMD, we were a bit skeptical. At the same time, the numbers we were hearing were impressive and AMD doesn't have a history of talking up that sort of thing to us. There have already been some investigations around the web that do point to the 4890 as having some healthy overclocking potential, so we decided to try our hand at it and see what we could come up with.

We are testing review samples, which means that our parts may have more overclockability than off the shelf cards, but we can't attest to that at this point. What we do want to explore are the overclocking characteristics of the 4890 and how different adjustments may or may not affect performance. From what we are seeing around the web, many people are getting fairly close to the speeds we tested. Every part is different, but while clock speeds may vary, the general performance you can expect at any given point will not.

So what's so special about this AMD part that we are singling it out for overclocking anaysis? Well, the GPU has been massaged to allow for more headroom, some of which hasn't been exploited at stock clock speeds. This is the first time in a long time (or is it ever?) we are seeing multiple manufacturers bring out overclocked parts based on an AMD GPU at launch. With this as the flagship AMD GPU, we also want to see what kind of potential it has to compete with NVIDIA's top of the line GPU.

But it's more than just the chip. We also are also interested in how well the resources on the board are balanced. Core voltages and clock speeds must be selected along with framebuffer size and memory clock. These considerations must account for a target power, heat, noise and price. For high end parts, we see the emphasis on performance over other factors, but there will still be hard limits to work within.

Because of all this, balancing hardware specifications is very important. Memory bandwidth needs to be paired well with core speed in order to maximize performance. It doesn't do us as much good to have an infinitely fast core if we have slow memory that limits performance. We also aren't well served by really ridiculously fast memory if the core can't consume data quick enough. Using resources appropriately is key. And AMD did a good job balancing resources with the 4890.

Rather than just test the semi-official overclock (which is just a 50MHz core clock boost to 900MHz), we decided to test multiple core and memory overclocks (and one core + memory overclock) to better understand the performance characteristics of this beast. As expected, overclocking both core and memory saw the best results followed by only overclocking the core. Just boosting memory speed on its own didn't seem to have a significant impact on performance despite the large overclock that was possible.

So why not sell every chip at the "overclocked" speed? Well, it's all about yield. Our guess is that while the change that AMD made were certainly good enough to boost clock speed over the 4870 by a healthy margin that there were a good number of parts that couldn't be pushed up to 900MHz and AMD really didn't want to sell them as cheaper hardware. We haven't heard that endorsing the idea overclocked parts is really a policy change for AMD, so it might just be that previous layout, routing, and design choices provided for a narrower range of overclockability around the target clock frequency.

What ever the reason for it, we now have overclockable hardware from AMD. Our analysis starts with an in depth look at percent increase in performance, but if all you care about is raw performance data, we've got plenty of that in the second half. And with it comes a surprise in our conclusion we never expected.

Cranking GDDR5 All the Way Up
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  • PC Reviewer - Monday, June 22, 2009 - link

    I can vouch for this card...


    I prefer the XFX.. but either way, any single one of those cards is outstanding...
  • fausto412 - Tuesday, May 5, 2009 - link

    All this talk of tuning video cards for max flexibility and performance beings to mind a great idea. why not have a write up on all the neat things you can do with Riva Tuner.i only know how to do 2 things. setup overclocking and fan profiles but i know there is more neat stuff in there.

    and can you undervolt an nvidia card with software? how?
  • ValiumMm - Tuesday, May 5, 2009 - link

    Saphire and Powercolor have both announced a 1ghz GPU for the 4890, IF this is what got, i just thought you guys would have got higher since your seeing the max OC
  • gold333 - Monday, May 4, 2009 - link

  • SiliconDoc - Saturday, June 6, 2009 - link

    Gee that's funny, the GTX275 wins against the 4890 in every single benchmark nearly - or everyone one completely.
    Gee imagine that - I guess Derek wasn't red roostering the testing with a special manufacturer edition sent exclusively to him from ati - and a pathetic 703 core nvidia.
    It's amazing what passes HERE for "a performance comparison".
  • gold333 - Monday, May 4, 2009 - link

    Overclocking Review: HD 4890


    Overclocking Review GTX 275


    Both are on the identical Core i7 system.
  • random2 - Monday, May 4, 2009 - link

    Great article Derek

    Thanks a ton for the not small effort made to put this together.

    What I found very interesting, (besides the overclockability of the 4890) was just how close the 4890 is to the 285 in resolutions less than 30" monitor size. Close enough to be within the realm of "margin of error".

    This is all good to know as I have a 24" monitor I cannot see giving up for a few years yet:-)

    Thanks again. Oh, by the way....Those who can do...Those who cannot....criticize.
  • rgallant - Thursday, April 30, 2009 - link

    -in every game ? when did this happen.
  • frozentundra123456 - Thursday, April 30, 2009 - link

    Just 2 topics:

    1. How would the 4890 compare in price and performance to the 4870x2 or 4850x2. Would these cards give similar performance at a lower price?

    2. When is DX11 coming, how will it be implemented, and will it be any more efficient hardware wise than DX10? Even now, most games take a serious performance hit with DX10. Will DX11 require even better hardware?? If so I will either have to do a serious upgrade or run 2 generation old DX9. I have played Company of Heroes and World in Conflict, and I ran both is DX9 mode. The games looked fine and performance was so much better. DX10 to me has been a big disappointment in that it is so resource intensive without much visual improvement.

  • Captain828 - Thursday, April 30, 2009 - link

    I have to say, this is probably the most worked out OC article I've ever seen... and I've seen a lot of them.

    Now I understand OC-ing the 4890 to show what a terrific overclocker it is, but it's just not fair to do this if you don't OC the competition's GPU in the same price range (the GTX 275).

    Also, I failed to see you mention db ratings in the article. No one wants a goddamn leaf blower in their PC for usual gaming purposes.

    Again, I know it took a lot of time and effort to get this done, but I would have gladly waited to see a GTX 275 OC comparison.


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