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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PrinceGaz - Wednesday, April 29, 2009 - link
Interesting certainly, but when I read Overclocking... to the max" my first thought that a large tub of LN2 would be used :pDerekWilson - Wednesday, April 29, 2009 - link
heh ... i'd love to play with some liquid nitrogen. that'd be great fun. i don't think we're going there anytime soon though.Veteran - Wednesday, April 29, 2009 - link
Why didn't you guys play with the fanprofiles? Added some VGPU with 3th party software? Just went to the realy maximum of the card. It would be amazing to see the results of that. Using 3th party software shouldn't be any limitation to overclocking if you ask me.DerekWilson - Wednesday, April 29, 2009 - link
We did set the fan on 100% manually all the time. Sure, it's a leafblower at that speed, but we wanted to keep it cool. Sorry I didn't mention that.It is possible to get some 4890 cards higher, but this wasn't an article for the hardcore overclocker. Rather we wanted to talk about what the average user can do out of the box by clicking a few buttons in the driver. Which, in my opinion, is more impressive than if we'd gotten an extra couple percent increase in core and memory clock speeds.
Not that even I wouldn't be interested in knowing how fast you could get one of these beasts ... It's just a different article than the one I wanted to write here.
SiliconDoc - Saturday, June 6, 2009 - link
It will be a nice day when you don't have to apologize ten times in every ati vs nvidia article for your massive ati biased BS Derek.--
" We did set the fan on 100% manually all the time. Sure, it's a leafblower at that speed, but we wanted to keep it cool. Sorry I didn't mention that. "
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All you red roosters aren't sorry - the enthusiasts see your charts and head off to redland purchse while your lying CRAP misdirects them ! And you know it - and are sickeringly proud of it no doubt !
It's been going on forver by you here !
PERIOD!
Veteran - Wednesday, April 29, 2009 - link
The title just imply different things then this review. That's all, i enjoyed reading it and see how the card responds to Core and Mem OC's. But if you use the words 'extravaganza' (very special) and 'to the max' people start thinking about dry-ice/ln2, voltage modifications etc.The article is awesome, the title is a little bit wrong
CyNics - Wednesday, April 29, 2009 - link
to Derek: have you tried overclocking the GeForce GTX 275, or at least comparing an OC'ed gtx275 with an OC'ed 4890 before coming to such conclusion?DerekWilson - Wednesday, April 29, 2009 - link
This is a pretty good question --These tests and the article took a while for me to put together. I am planning on doing a GTX 275 overclocking and seeing if anything interesting happens. If I get good results I'll put together an article on the subject.
I tried pretty hard to keep this article on the subject of the 4890 itself and where I made comparisons it was to hardware outside it's price class with the GTX 285.
No matter how well the GTX 275 does, the 4890 still did as well as it did versus the GTX 285 (and relative to itself).
If I screwed up and made direct comparisons between overclocked 4890 and GTX 275 or something, let me know and I'll fix it 'cause I didn't mean to. Otherwise I hope that this article is as appropriate as I wanted it to be.
Once I've also overclocked the GTX 275 I'll have something to say about it's relative value versus the 4890 in that regard.
SiliconDoc - Saturday, June 6, 2009 - link
THAT'S AN AMAZING BIT OF BS DEREK !" If I screwed up and made direct comparisons between overclocked 4890 and GTX 275 or something, let me know and I'll fix it 'cause I didn't mean to. Otherwise I hope that this article is as appropriate as I wanted it to be.
Once I've also overclocked the GTX 275 I'll have something to say about it's relative value versus the 4890 in that regard. "
First you say IF you used a non overclocked GTX275 and screwed up doing it - someone should point it out (because you obviously can't see it in your own charts - right red rooster?) - and if someone points out your massive idiots bias, you'll change it otherwise you won't... THEN YOU ADMIT YOU HAVEN'T OVERCLOCKED THE GTX275 YET ! PROVING ABSOLUTELY YOU DID IN FACT COMPARE IT NON OVERCLOCKED TO THE 4890 SPECIAL MANUFACTURERS EDITION SENT TO YOU !
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SO WHAT THE HELL DID YOU MEAN BY " If I screwed up and made direct comparisons between overclocked 4890 and GTX 275 or something, let me know and I'll fix it 'cause I didn't mean to." ?!!???
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YOU DID IT DEREK - YOU KNEW YOU DID IT, YOU DID IT "ON PURPOSE" THEN EVEN AS YOU DENY IT AFTER BEING QUESTIONED, YOU ADMIT IT INCRIMINATING YOURSELF !
YOU EVEN ASK THE QUESTONER POINT IT OUT WHEN YOU DID THE CHARTS AND THE TESTS HERE !
MY GAWD!
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Dude, if you think your BS is even passable, THINK AGAIN !
SiliconDoc - Saturday, June 6, 2009 - link
Yes, our great masterous "fair" and "unbiased" reviewer Derek.
DOESN'T EVEN KNOW WHEN HE IS COMPARING OC'ED SPECIAL MANU. TO STOCK !
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WHAT a genius! Keep that boy hired ! Must be worth a whole 50 cents an hour, if that !