Overclocking Extravaganza: GTX 275's Complex Characteristics
by Derek Wilson on June 4, 2009 5:35 AM EST- Posted in
- GPUs
Memory Overclocking
Data availability is important in the performance of GPUs, and AMD and NVIDIA pack huge amounts of bandwidth into their designs in order to accommodate this need. While AMD's high end parts have moved over to the newer, less tested, GDDR5, NVIDIA will stick with GDDR3 until at least their next architecture revision (though it is still unclear exactly what memory technologies NVIDIA will support beyond the current generation). This does mean that NVIDIA needs twice the number of pins to achieve the same bandwidth (at the same clock speed), but this isn't a huge problem for the already monolithic G80 and GT100 based GPUs.
With the 448-bit wide connection to GDDR3 memory, NVIDIA's GTX 275 needs to run it's RAM at a higher clock speed in order to achieve the same data rate the Radeon 4890 can hit with it's 256-bit GDDR5 bus. Certainly fast GDDR3 has had time to mature and is highly available. This and the fact that demand is still much higher for GDDR3 mean that NVIDIA is saving some money on competitive memory subsystems. But needing a higher baseline clock speed to compete with AMD's solution could mean less overclockability overall.
We were able to get a greater than 23% clock speed increase out of our 4890, but the best we could manage between a couple of GTX 275 samples was a little more than 14%. Starting out with very nearly the same memory bandwidth, our overclocked AMD part comes out ahead in absolute terms.
It is important to remember, however, that absolute bandwidth doesn't matter as much as how well the bandwidth matches the demand of the GPU. This isn't something we can easily ascertain, but our look at the impact of only overclocking memory certainly shows that the bandwidth NVIDIA chose for the GTX 275 is a good match for the core and shader clock speeds with which it is paired.
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We will be digging deeper into how memory speed impacts performance after we look at the rest of our scaling tests, but without any other assistance, just overclocking memory is not going to gain a lot for the GTX 275.
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balancedthinking - Thursday, June 4, 2009 - link
Actually, you can save as much as 40W(!)idle when you underclock a 4890/4870. The important part is to underlcock the GDDR5 which automatically adjusts voltage too.http://www.computerbase.de/news/hardware/grafikkar...">http://www.computerbase.de/news/hardwar...ten/ati/...
7Enigma - Friday, June 5, 2009 - link
Anyway you could translate the 4870 portion? Babelfish is not working for me for some reason....jeramhyde - Thursday, June 4, 2009 - link
great article thanks :-) good work with the graphs and setting it out in an easy to follow way :-)my housemate just got a gtx275 today, so we'll be trying those overclocks tonight :-)
nvalhalla - Thursday, June 4, 2009 - link
Alright, I just spent the last 10 minutes looking for a 900 shader 4980 before I realized you meant a 900MHz 4890. It's wrong in every graph.DerekWilson - Thursday, June 4, 2009 - link
It's not wrong, it's just noted in a different way.like I say (702 core) for the GTX 275 with a 702MHz core clock, i say (900 core) for a 4890 with a 900MHz core clock.
I'm sorry for the confusion, but it the graphs were already so crowded that I wanted to save space as much as I could.
nvalhalla - Thursday, June 4, 2009 - link
no, you're not getting me. It's listed as a 4980, not a 4890. I thought it was a new card, the "NEXT TIER" if you will. The 900 I thought might be a reference to the number of SP. Once I realized you just transposed the numbers, I got the 900 was MHz.DerekWilson - Thursday, June 4, 2009 - link
oooooooooooohhhhhhhhh ... okay ... that's a fun typo. I can't really do search and replace on these graphs either. I'll try and get it cleaned up as soon as I can.thanks for clarifying.
walp - Thursday, June 4, 2009 - link
Very nice article as always! :)GTX275 and 4890 is really evenly matched in every different way(Price, performance, overclocking performance etc) except for the fact that 4890 can be used with the 19$ Accelero S1:
http://translate.google.com/translate?prev=hp&...">http://translate.google.com/translate?p...mp;sl=sv...
, which makes it totally quiet and cool. Just watch those VRM-temperatures and you will be just fine!
This is the main reason why I chosed the 4890 over GTX275, and the fact that I had a CF-compatible motherboard.
By the way, why didnt you include the 4890 (1\1.2)GHz idle power draw? Or is it just a little type-o? :)
Request: GTX275 SLI vs 4890 CF (And overclocking bonanza! :)))))
\walp
SiliconDoc - Monday, June 22, 2009 - link
I can't help but use google and check the very first site that comes up:http://www.techspot.com/review/164-radeon-4890-vs-...">http://www.techspot.com/review/164-radeon-4890-vs-...
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and the GTX275 beats the TAR out of the 4890 !!!
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I guess derek has once again used some biased bench or the special from the manufacturer 4890, and then downclocked the GTX275 to boot.
WHAT A CROCK !
SiliconDoc - Saturday, June 6, 2009 - link
It's hilarious - the extravaganza overclock they do here for Nvidia can't even match the stock timings of a common EVGA.http://www.newegg.com/Product/Product.aspx?Item=N8...">http://www.newegg.com/Product/Product.aspx?Item=N8...
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core 713 derek weakness red rooster nvidia hate 703
So what AT has done here is put the 4890 max overclocked in their other article against a low end stock gtx275, then in their extravaganza overclock gtx275 they put up a pathetic overclock that is BEATEN BY An EVGA gtx275 as it arrives !
Worse yet, they jammed their ati 4890 maxxxxx overclocks in for comparison !
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How to be a completely biased load of crap by Derek and AT :
max overclock your ati 4890 and put stock gtx275's against it
weak overclock your gtx275 and put maxx overclock 4890's against it
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ROFLMAO - I HAVE TO LUAGH IT'S SO BLATANT AND PATHETIC.
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cocka doodle doooo ! cocka doodle dooo ! red rooster central.