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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lopri - Thursday, April 30, 2009 - link
It's my impression that AMD cards are more responsive to clock frequencies, while NV cards are rather dependent on units/clusters. We've seen it from GTX 260 vs. GTX 280, as well as 8800 GTS vs. 8800 GTX. There were situations where GTX 280 / 8800 GTS can't come over the performance of their older brothers, even with massive overclocking. (and their clock generator don't generate clocks linearly)Just a thought.
Depeche - Wednesday, April 29, 2009 - link
BTW, great article but very long and time consuming xD to interesting. Keep up the great work!Depeche - Wednesday, April 29, 2009 - link
Doesn't AMD make the cards a whole different way then Nvidia? Don't they have like really high clocks and memory while Nvidias is a lot lower with higher of other parts?Also has Nvidia made a card that's simply overclocked like the 4870/4890?
SiliconDoc - Saturday, June 6, 2009 - link
ATI has lost TWO BILLION DOLLARS SELLING THEIR GPUs ! A BILLION A YEAR EASY - YET DEREK HAS THE UNMITIGATED GAUL TO SAY THIS:.
" In the meantime, NVIDIA's margins are much tighter on their larger GPUs and now their single GPU performance advantage has started to erode. It seems the wonders of the RV7xx series have yet to exhaust themselves. "
ROFLMAO !
THAT MIGHT MAKE SENSE IF ATI HADN'T COST AMD A BILLION PLUS A YEAR ON BARELY 2 BILLION IN SALES! ATI IS LOSING 33%.
THEY SELL $100's OF ATI CARD, THEY LOSE $33 !
---
THE TRUTH REALLY REALLY SUCKS , HUH RED ROOSTERS !
SiliconDoc - Saturday, June 6, 2009 - link
depeche: " Doesn't AMD make the cards a whole different way then Nvidia? Don't they have like really high clocks and memory while Nvidias is a lot lower with higher of other parts?Also has Nvidia made a card that's simply overclocked like the 4870/4890?
"
THE ARTICLE HERE " 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. "
LOL - WELL THAT SHOULD ANSWER YOUR QUESTION !
cocka doodle dooooo ! cocka doodle doo ! red rooster rides again !
ValiumMm - Tuesday, May 5, 2009 - link
lol noooobkmmatney - Wednesday, April 29, 2009 - link
I had an NVidia Ti4200 that overclocked well - good enough to basically double the cards value. The original Radeon LE also overcloked well, and you could unlock extra pipes. I also still have an X800GTO2 that could be Bios flashed to an X850XT.nubie - Wednesday, April 29, 2009 - link
I am not sure I understand what you mean by "simply overclockable"Just add the coolbits registry value to the classic control panel and there are two simple sliders. It has been that way for years.
As far as the speeds you can reach, just take care that there is enough cooling and power (voltage bumps if need be).
I learned how to shade a resistor and take voltage measurements over at vr-zone, I think Shamino has a tutorial for it.
StevoLincolnite - Wednesday, April 29, 2009 - link
The most Overclockable card that I can remember from nVidia was the Geforce FX 5700LE it's stock core speed was 250mhz, I managed to crank my core speed on that card all the way to 640mhz on the stock Heatsink and fan, however thats not saying much as the 5700LE was basically a regular 5700 but with it's clockspeeds reduced to 5200 speeds, before that I had a Geforce 2 MX100 which was incredibly overclockable, and the TNT Vanta I had before it was as well, however I don't think I have seen a high-end part with that much overclocking margin.nubie - Wednesday, April 29, 2009 - link
If you are willing to raise the voltage you can get really good overclocks.I had a 7900GS up to 720mhz (from 450mhz) before it couldn't take it. Backing off to 708-700 made it stable, so I settled for 650 and it has been rock-solid for 3 years.
It all depends on the kind of cooling and power you can bring it.