One thing we unfortunately had to cut out of our AMD ATI Radeon HD 4770 review yesterday was overclocking. Understandably, a number of our readers asked why we'd not bothered to overclock the card.
The answer is that we simply ran out of time when we made the decision to double (and triple) check all of our Far Cry 2 performance numbers when the new Radeon came out on top against the cards we'd compared it to. Although the results were theoretically possible - compared to the much-loved Radeon HD 4850, it has a higher pixel fillrate and very similar theoretical shader throughput (it's just four percent lower), we wanted to be not just doubly sure, but triply sure before publishing our conclusions.
Yesterday afternoon, I dragged myself back down into the benchmarking sweatshop that is the bit-tech and Custom PC labs to find out how well our reference card overclocked. It's worth noting that it's not the only Radeon HD 4770 we've got in house - there are a couple of partner cards already and we'll be looking at them in due course - but we've only focused on overclocking the reference card for now.
[break]
We first set about overclocking the Radeon HD 4770 using the tools provided to us by AMD - the ATI Overdrive section in Catalyst Control Center. With this, we quickly hit problems... not nasty problems, but good problems - we were limited by the software and hit Catalyst Control Center's maximum clocks of 830MHz core and 850MHz (3,400MHz effective) memory.
The card was showing no temperature or stability issues - everything was very much under control. But we couldn't overclock any further without finding another tool.
We turned to an old friend of ours, RivaTuner, which currently doesn't have official support for the 4770. However, the great thing about the tool is that you can add support by modifying the configuration files. Hilbert from Guru3D was on hand to help us with the hex codes required to get RivaTuner to recognise RV740 - you simply need to add '94B3h' to rivatuner.cfg on the RV770 line under the '[GPU_1002]' section, to make the line read like so:
After doing this, simply restart RivaTuner and it'll allow you to adjust the clocks in the overclocking section. There are some bugs, though - RivaTuner does misreport the ASIC and the core frequency monitoring doesn't work, but I'm sure they'll be fixed in the next RivaTuner release. This is where GPU-Z comes in, because that reports the chip's details and clock speeds correctly.
We could then set about continuing our quest to find the Radeon HD 4770's limit... and we were pleasantly surprised.
Without adjusting the fan speed profiles with the card installed in an Antec Twelve Hundred chassis with no direct airflow to the card, we managed to get the GPU core up to 880MHz and the memory to 985MHz (3,940MHz effective). That's a 17.3 percent core speed increase and a 23 percent improvement in memory bandwidth, which now sits at 63.0GB/sec, which isn't too far off the 4850's 64.0GB/sec.
In terms of performance - here's what we found...
It's still a little memory bandwidth limited with anti-aliasing enabled, but even then the gap between the Radeon HD 4770 and Radeon HD 4850 has almost completely disappeared. When anti-aliasing is disabled, the overclocked 4770 ends up in another league - not bad for a card that costs £30 less, eh?
And while we're on that topic, we should probably mention that the Radeon HD 4770 is shipping for under £80 already. Prior to the launch, we were quoted an £86.99 retail price by AMD and we managed to find the card for £83 - it's fair to say we were a little hesitant to give a strong buying recommendation on launch day because things chop and change quicker than who's in the manager's chair at Newcastle Football Club.
At this price though, we strongly recommend buying the card over anything else within spitting distance. And that includes the GeForce GTS 250 currently selling for around £97 - it's not far off a 25 percent increase in price and you're definitely not getting 25 percent extra performance in most scenarios!
The answer is that we simply ran out of time when we made the decision to double (and triple) check all of our Far Cry 2 performance numbers when the new Radeon came out on top against the cards we'd compared it to. Although the results were theoretically possible - compared to the much-loved Radeon HD 4850, it has a higher pixel fillrate and very similar theoretical shader throughput (it's just four percent lower), we wanted to be not just doubly sure, but triply sure before publishing our conclusions.
Yesterday afternoon, I dragged myself back down into the benchmarking sweatshop that is the bit-tech and Custom PC labs to find out how well our reference card overclocked. It's worth noting that it's not the only Radeon HD 4770 we've got in house - there are a couple of partner cards already and we'll be looking at them in due course - but we've only focused on overclocking the reference card for now.
[break]
We first set about overclocking the Radeon HD 4770 using the tools provided to us by AMD - the ATI Overdrive section in Catalyst Control Center. With this, we quickly hit problems... not nasty problems, but good problems - we were limited by the software and hit Catalyst Control Center's maximum clocks of 830MHz core and 850MHz (3,400MHz effective) memory.
The card was showing no temperature or stability issues - everything was very much under control. But we couldn't overclock any further without finding another tool.
We turned to an old friend of ours, RivaTuner, which currently doesn't have official support for the 4770. However, the great thing about the tool is that you can add support by modifying the configuration files. Hilbert from Guru3D was on hand to help us with the hex codes required to get RivaTuner to recognise RV740 - you simply need to add '94B3h' to rivatuner.cfg on the RV770 line under the '[GPU_1002]' section, to make the line read like so:
RV770 = 9440h-9442h,944Ch,94B3h
After doing this, simply restart RivaTuner and it'll allow you to adjust the clocks in the overclocking section. There are some bugs, though - RivaTuner does misreport the ASIC and the core frequency monitoring doesn't work, but I'm sure they'll be fixed in the next RivaTuner release. This is where GPU-Z comes in, because that reports the chip's details and clock speeds correctly.
We could then set about continuing our quest to find the Radeon HD 4770's limit... and we were pleasantly surprised.
Without adjusting the fan speed profiles with the card installed in an Antec Twelve Hundred chassis with no direct airflow to the card, we managed to get the GPU core up to 880MHz and the memory to 985MHz (3,940MHz effective). That's a 17.3 percent core speed increase and a 23 percent improvement in memory bandwidth, which now sits at 63.0GB/sec, which isn't too far off the 4850's 64.0GB/sec.
In terms of performance - here's what we found...
It's still a little memory bandwidth limited with anti-aliasing enabled, but even then the gap between the Radeon HD 4770 and Radeon HD 4850 has almost completely disappeared. When anti-aliasing is disabled, the overclocked 4770 ends up in another league - not bad for a card that costs £30 less, eh?
And while we're on that topic, we should probably mention that the Radeon HD 4770 is shipping for under £80 already. Prior to the launch, we were quoted an £86.99 retail price by AMD and we managed to find the card for £83 - it's fair to say we were a little hesitant to give a strong buying recommendation on launch day because things chop and change quicker than who's in the manager's chair at Newcastle Football Club.
At this price though, we strongly recommend buying the card over anything else within spitting distance. And that includes the GeForce GTS 250 currently selling for around £97 - it's not far off a 25 percent increase in price and you're definitely not getting 25 percent extra performance in most scenarios!
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October 14 2021 | 15:04
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