Overclocking Extravaganza: GTX 275's Complex Characteristics
by Derek Wilson on June 4, 2009 5:35 AM EST- Posted in
- GPUs
Core Overclocking
After G80 hit (the first NVIDIA GPU to employ a separate clock domain for shaders), silent shader clock speed increases were made with any core clock speed increase. At first this made sense because NVIDIA only exposed the ability to adjust core and memory clock and the shader clock was not directly adjustable by the end user. Of course, we went to some trouble back then to try our hand at BIOS flashing for shader overclocking. After NVIDIA finally exposed a separate shader adjustment, they still tied core clock and shader clock to some degree.
Since the middle of last year, NVIDIA's driver based clock speed adjustments have been "unlinked," meaning that the shader clock is not affected by the core clock as it used to be. This certainly makes things a lot easier for us, and we'll start by testing out core clock speed adjustment.
The maximum core clock we could hit on our reference GTX 275 was 702. Try as we might, we just could not get it stable beyond that speed. But it's still a good enough overclock for us to get a good handle on scaling. We know some people have GTX 275 parts that will get up toward 750 MHz, so it is possible to get more speed out of this. Still, we have an 11% increase in core clock speed which should net us some decent results.
1680x1050 1920x1200 2560x1600
Call of Duty edges up toward the theoretical maximum but drops off up at 2560x1600 which is much more resource intensive. Interestingly, most of the other games see more benefit at the highest resolution we test hitting over 5% there but generally between 2 and 5 percent at lower resolutions. FarCry 2 and Fallout 3 seem not to gain as much benefit from core overclocking as our other tests.
It could be that the fact we aren't seeing numbers closer to theoretical maximums because there is a bottleneck either in memory or in the shader hardware. This makes analysis a little more complex than with the AMD part, as there are more interrelated factors. Some aspects of a game could be accelerated, but if a significant amount of work is going on elsewhere, we'll still be waiting on one of the other subsystems.
Let's move on to the last independent aspect of the chip and then bring it all together.
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Shadowmage - Thursday, June 4, 2009 - link
Evenly matched? The 4890 OCed beats the GTX275 OCed in almost all benchmarks and wins considerably in every game at the resolution that I play at: 1680x1050. It also uses substantially less power and costs less than $200 (eg. ewiz deal at $160, newegg deal at $180), whereas the GTX275 still costs upwards of $220.walp - Thursday, June 4, 2009 - link
I just wanted to be polite. :4890 @ 1\1.2 is a really nice overclock. They do mention that the GTX275 did'nt overclock that well.
So I prefer (to be aside of the fanboyism-spectra) to call them evenly matched when talking about performance.
Good for you that 4890 is so cheap over there, here they cost about the same as the GTX275. (280$) :/
Powerdraw from a electrical cost-point of view is unimportant for me, since I have free electricity. (Long live the swedish King! lol..) ;)
But it is better from a heat-point-of-view to have less power-draw of course, yeah, so 4890 is (again:slightly) better than GTX275 at load. Its the other way around for idle though. (I would sincerely call this evenly matched in powerdraw).
I have no clue whatsoever how they compare when it comes to noise, but 4890 is really loud at load, thats for sure. ('But not anymore its not!')
\walp
Carfax - Thursday, June 4, 2009 - link
Except that the GTX 275 OC had a very moderate overclock compared to the greater overclock on the HD 4890.I don't see how Anandtech only got 700mhz out of the core.
li3k - Thursday, June 4, 2009 - link
well...A cursory search on google yieled the highest core overclocks obtainable on gtx 275 boards to be between 700 and 745mhz. If you can show us otherwise, please do.
As for myself, and other hardware enthusiasts I'd imagine, the maximum potential of a card comes from its maximum overclocked performance. The fact that the gtx 275 had a "moderate" maximum overclock compared to the 4890 should not come at the cost of the 4890 in a potential comparison.
I stand by my point.
Carfax - Thursday, June 4, 2009 - link
I just googled "GTX 275 overclock" and the first article that pops up is from Guru3d which shows the GTX 275 overclocking to 743mhz.Tweaktown did another one and got 715mhz, but they had no clue what they were doing and left the shaders linked.
Anyway, the point is though, if you're going to do an article on overclocking the GTX 275, why bother with a card that has such poor overclocking capability?
Anandtech's HD 4890 OC article specifically used an HD 4890 that was capable of hitting 1ghz on the core, because not all HD 4890s are capable of attaining such a high core speed.
Why couldn't they do the same for the GTX 275?
This article is B.S..
SiliconDoc - Saturday, June 6, 2009 - link
LOLYou can buy a GTX275 retail at 713 core - and they got theirs all the way up to 703 here ! roflmao
Worse yet they use their 4890 numbers from their specially delivered non retail "golden ATI secret channel" - as Derek the red rooster says here in their 4890 oc extrava article ! - LOL
" 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. "
http://www.anandtech.com/video/showdoc.aspx?i=3555...">http://www.anandtech.com/video/showdoc.aspx?i=3555...
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SO THE BIAS IS BLEEDING OUT LIKE A BIG FAT STUCK PIG... IF YOU HAVE ANY SENSE WHATSOEVER THAT IS...
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a red rooster fanboy like Derek and all his little raging red roosters here love it.
li3k - Thursday, June 4, 2009 - link
I have to agree...vote me down if you like, but the way this article is worded just reinforces the commonly held assumption that anandtech is biased towards intel/nvidia.
DerekWilson - Thursday, June 4, 2009 - link
thanks for the feedback ... but I'm not touching overclocked SLI and CF ... ugh!I didn't include the 4890 1/1.2 in idle power because it is redundant as it doesn't affect idle power. and came in at the same idle power as the other two. I wanted to save on graph space where i could because there was so much data -- plus we already covered that in the 4890 overclocking article. Sorry if I dropped too much out.
walp - Thursday, June 4, 2009 - link
Hmm, mkay.Was just confused by the fact that the sligthly overclocked 4890 wanted less juice than the original version in idle.
Maybe due to better VRM\mosfet underclocking or whatever. :)
At least do GTX275 SLI vs. 4890 CF, (and while doing that, just overclock them slightly, plz ;)
I have my finger on the 'ordering-another-4890-button', but wont buy another until anandtech.com reviews 4890 CF!
\walp
SiliconDoc - Monday, June 22, 2009 - link
Yes the gtx 275 wins even in overclocking... i wonder what went wrong with dereks tests...( no i don't !)...
http://www.techspot.com/review/164-radeon-4890-vs-...">http://www.techspot.com/review/164-radeon-4890-vs-...