Overclocking Extravaganza: Radeon HD 4890 To The Max
by Derek Wilson on April 29, 2009 12:01 AM EST- Posted in
- GPUs
Exploring Core Overclocking
Adjusting core clock speed has a much higher impact on performance than only adjusting memory speed. At stock clock speeds the 4890 is much more compute bound than memory bound, and this is where the difference comes in. While the 900MHz core clock variant will not offer huge performance gains over the stock card, the performance gains will be fairly proportional to the clock speed increase.
Despite the fact that a 50MHz bump only offers a maximum potential average performance improvement of about 6%, we often see realized performance gains of between 3% and 5% on 900MHz core clocked 4890 hardware. This is certainly a much better return than we saw even with a 23%+ memory overclock. Even so, 5% real world performance isn't the holy grail. So we decided to test multiple core clock frequencies ranging from 850MHz to 1000MHz in 50MHz increments. For these tests, we fixed memory clock speed at 975MHz.
Let's jump right in and talk about 1000MHz. Here's a look at what we get from this boost in clock speed.
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In non-CPU limited situations, the approximately 10% to 13% performance improvement out of a potential 17.6% improvement is nothing to sneeze at. Here's the break down of percent increase in performance at the different clock speeds we tested across three resolutions in all the games we tested.
At each speed bump we a pretty good proportional performance improvement. We are closer to the theoretical max at the more modest clock speed increases than at the high end though. This could potentially mean that our core clock speed increases are creating memory bottlenecks. It is clear that even without any potential boost from an accompanying memory overclock, the 4890 is potentially capable of some impressive clock speeds and performance. Despite the fact that we want to be thorough, we can't test all of these core clock speeds with multiple different memory clock speeds, as the testing would quickly balloon. So we compromised a bit, but the results on the next page speak for themselves.
We absolutely must caution our readers once again that these are not off-the-shelf retail parts. These are parts sent directly to us from manufacturers and could very likely have a higher overclocking potential than retail parts. From what we are hearing in the field, though, many people have been able to achieve a decent boost in clock speed with the 4890.
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gold333 - Monday, May 4, 2009 - link
Guru3d has OC reports of both. The GTX275 seems to be clearly in the lead.SiliconDoc - Saturday, June 6, 2009 - link
" Guru3d has OC reports of both. The GTX275 seems to be clearly in the lead. "--
This is red roosterville. Compare the special edition from manufacturer ATI 4890 to the standard or sub OC GTX275, then spin it up more for the red roosters with special custom game profiles, resolution and game settings, and leave PhysX ON even if the game doesn't use it.
Post the massively biased results and provclaim ATI the overall superking winner.
Allow your red rooster fanbase and anyone else enjoy the fantasy, while lying as much as possible, and apologizing every time the bias is pointed out by a poster, claiming you didn't know, you'll fix it, that's a good question, you'll get to it, you didn't mean to compare Oc'ed ATI to stock GTX275 - etc etc etc .
--
That's why other reviews so often show the GTX275 way ahead. Not every single one - there are more red rooster stations about, but hey, some people like Derek just can't help themselves.
joeysfb - Thursday, April 30, 2009 - link
How to be fair?.. Overclocking is subjective in nature... So if Derek's card can overclock to 1G/1.2G and the one i bought can't do it. What's next?...This article is about 4890, GTX275 will have another article for itself. Beside, you are pretty fix that GTX275 is the better card anyway...
ira176 - Wednesday, April 29, 2009 - link
I've heard the rumor that the Radeon HD 5000 is around the corner, but will ATI incorporate 40 nm tech into the HD 4870 and 4890?Wouldn't it be a pretty neat card if Sapphire could get their hands on an HD 4890 with 40 nm tech and the Vapor-X cooling solution!
Shadowmage - Wednesday, April 29, 2009 - link
... you could have presented the graphs in a much more readable manner. The only thing you were really doing was finding the Amdahl's Law curves for the part.Watch out for sentence fragments in the future too :)
As an aside, usually mainstream hardware reviewers are absolutely horrible and incompetent at overclocking, so it's refreshing to see some results that actually match what end-users have been reaching on various enthusiast forums (~1GHz core clocks on stock air).
DerekWilson - Wednesday, April 29, 2009 - link
Thanks for the suggestions. Can you email me the sentence fragments :-)And actually we'd probably see more overclocking articles if I didn't take it seriously... I'm not the best at it, but I do what I can.
corporategoon - Wednesday, April 29, 2009 - link
Quite a few folks in here are talking about messing with voltages - how do you do this? I have a 4870 with a thermalright cooler and I'd love to mess with voltages to get some extra performance out of it, but have had no luck searching for a utility that'll let me do this.DerekWilson - Wednesday, April 29, 2009 - link
the ASUS card we tested actually comes with a utility to tweak its voltage. there are some hardware mods out there as well ... if you're really hard core you can go check out mvktech.net and download some bios readers/writers and editors and really go crazy (and possibly destroy your card).but there are options.
our tests were done without voltage mods.
walp - Wednesday, April 29, 2009 - link
Awesome test!I bought the 4890 for three reasons:
-Its funny to overclock and see the range soooaaAAaaaar!
-Its relatively cheap for top of the line performance (when overclocked to 1000\1150 @ 1.43V ^^) as you can clearly see!
-Its totally compatible with the accelero s1 which currently keeps my GPU below the 64°C at full load furmark. And its soooo silent! Gotta love it! 19 bucks for a kick ass cooler!
Enjoy the silence, and powah! :D
And when the games become more demanding, I will buy another one! (hopefully a lot cheaper, and a lot more developed x-fire drivers!)
Cause, I can play Crysis 1920x1080, very high, everything maxxed in Catalyst 8x AA, 16x AF etc. ~40-50fps AWESOME-O! :D
(4.4GHz E8500, 4GB ram)
Its a pity though that it costed me 2500kr incl. shipping (~300$) here in sweden, but its worth every Krona! :)
kmmatney - Wednesday, April 29, 2009 - link
Thanks for letting me know that it's compatible with the accerero S1! I would love this card if it were a little more quiet. Is this the one you have?http://www.newegg.com/Product/Product.aspx?Item=N8...">http://www.newegg.com/Product/Product.aspx?Item=N8...
Where did you get it for $19? I see this one for $19:
http://www.newegg.com/Product/Product.aspx?Item=N8...">http://www.newegg.com/Product/Product.aspx?Item=N8...
With my HD4890, there's a lot of heat coming out the back vent, so I'm a bit leary about using something like this, but if it makes the card cooler and quieter, then I'm all for it.