It will be worthwhile to test the X1900GT and X1800GTO. Dongle-less Crossfire depends entirely on the PCIe interface for inter-card communication; it may expose a significant bottleneck in the 965 board's PCIe x4 slot. And realistically, many users who decided to save a few bucks with a 965 board will probably want to use these mainstream cards.
I have also heard somewhere that running two X1900GTs in Crossfire requires a RD580 board. Always wondered if it's true, because then Conroe users effectively lose this option.
Interesting phrase, as I thought SLI is not officially supported on any of these two platforms:
This simply means that as games become increasingly complex and data bandwidth increases then the differences between the P965 and 975X in CrossFire or SLI operation will widen.
This was more of a forward looking statement (already addressed the unofficial SLI driver situation) and also to address any issues with readers saying they can run SLI on their Intel boards now. If NVIDIA and Intel ever come to an agreement then the statement holds true, if you decided to run the unofficial SLI drivers on the P965 then the overhead from the hacked drivers along with the DMI slowdown will create a performance delta between the 975X and P965.
Gary, nice article. I think it is the first time I see a comparison on the performance hit caused by the x4 bottleneck. It would be interesting also to see in a future article how does a pair of 7900 GTXs running in SLI using the hacked drivers stacks against the XFire solution.
I wonder if this move will drive Nvidia in the future to allow also SLI on the 975 or 965 chipsets. We know it can be done, perhaps it is a commercial or licensing problem that is blocking it.
Hell no! Not for this type of article - leave the scaling graphs in place. I would much rather see one graph (with numbers below) showing how cards scale from 1280x1024 through 1920x1200 instead of three separate graphs. Single bar charts are only effective when showing one data set.
Does overclocking the FSB (holding memory and cpu clocks constant) help alleviate some of the bandwidth and timing issues? Or, does overclocking the FSB not affect transfer rates between the MCH and ICH?
If the latter is the case, then who will be the first manufacturer to step up with MCH/ICH bus overclocking?
Any thoughts from the anandtech folks about a follow up article, or have you already tried increasing the FSB?
I am working on the overclocking aspects today. I just received the final bios code so I will update the article this weekend if there is a significant change in performance when overclocking both chipsets. If not, I will comment on it in here.
Skimp on the motherboard? If you buy an E6400 and want to overclock you would not get a 975x board anyway. You would get a 965 board because they achiegve much much higher FSB. It's not going cheap at all, it's actually playing smart.
No? Thanks for telling me, and everyone else what we'd do . . . The latest ABIT 975x board is looking rather attrative, and I know I'm not alone here. Anyhow, why would I step backwards in time, for overclocking, especially when the added performance boost really isnt worth it ? Memory compatability issues ? Lack of SLI support ? I think I'll spend a little more for current technology.
It's only playing it smart, if all you care about is overclocking. Alot of us who are enthuiasts, also care about stability, which means the system in question needs to be up for more than a few days. All my systems MUST be up for months at a time, and if they dont 'pass' this qualification *something* changes until they do. Its been my experience that systems pushed to the edge, often only exibit at best, a few days up time before a crash. Often times, this behavior includes mild overclocks aswell.
In a word, NVIDIA. All they need to do is support SLI on non-NVIDIA chipsets and it would work. SiS did a driver hack a while ago for their chipset, but NVIDIA nuked that with the next driver release... and bought up SiS just for good measure.
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22 Comments
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Madellga - Monday, September 25, 2006 - link
http://www.xtremesystems.org/forums/showthread.php...">http://www.xtremesystems.org/forums/showthread.php...Coolaler has posted on XS some benchmarks for SLI on 975 and 965 chipsets.
True, there are small differences between the setups (FSB and multis), but CPU speed was close enough.
You can see an impact between 15% and 20% for going from the 975 to 965 when running SLI with hacked drivers.
This other thread has SLI on the 965 for a 7600GT, but no comparison to the 975
http://www.xtremesystems.org/forums/showthread.php...">http://www.xtremesystems.org/forums/showthread.php...
Gary Key - Monday, September 25, 2006 - link
I have seen basically the same results in internal testing here, just that I cannot publish those numbers. ;-)Maruta731 - Saturday, September 23, 2006 - link
It will be worthwhile to test the X1900GT and X1800GTO. Dongle-less Crossfire depends entirely on the PCIe interface for inter-card communication; it may expose a significant bottleneck in the 965 board's PCIe x4 slot. And realistically, many users who decided to save a few bucks with a 965 board will probably want to use these mainstream cards.I have also heard somewhere that running two X1900GTs in Crossfire requires a RD580 board. Always wondered if it's true, because then Conroe users effectively lose this option.
Gary Key - Monday, September 25, 2006 - link
I will get a board up to Derek for further testing shortly. I do not have the dongle-less CrossFire cards at this time.jive - Monday, September 25, 2006 - link
Interesting phrase, as I thought SLI is not officially supported on any of these two platforms:This simply means that as games become increasingly complex and data bandwidth increases then the differences between the P965 and 975X in CrossFire or SLI operation will widen.
Any comments?
Gary Key - Monday, September 25, 2006 - link
This was more of a forward looking statement (already addressed the unofficial SLI driver situation) and also to address any issues with readers saying they can run SLI on their Intel boards now. If NVIDIA and Intel ever come to an agreement then the statement holds true, if you decided to run the unofficial SLI drivers on the P965 then the overhead from the hacked drivers along with the DMI slowdown will create a performance delta between the 975X and P965.Madellga - Saturday, September 23, 2006 - link
Gary, nice article. I think it is the first time I see a comparison on the performance hit caused by the x4 bottleneck. It would be interesting also to see in a future article how does a pair of 7900 GTXs running in SLI using the hacked drivers stacks against the XFire solution.I wonder if this move will drive Nvidia in the future to allow also SLI on the 975 or 965 chipsets. We know it can be done, perhaps it is a commercial or licensing problem that is blocking it.
nlr_2000 - Sunday, September 24, 2006 - link
But like the article pointed out, it's not the x4 PCIe slot but the interface between the Northbridge/Southbridge causing the performance hit.formulav8 - Saturday, September 23, 2006 - link
Please bring back the bar graphs. That is all.Jason
Frumious1 - Saturday, September 23, 2006 - link
Hell no! Not for this type of article - leave the scaling graphs in place. I would much rather see one graph (with numbers below) showing how cards scale from 1280x1024 through 1920x1200 instead of three separate graphs. Single bar charts are only effective when showing one data set.SLIM - Saturday, September 23, 2006 - link
Does overclocking the FSB (holding memory and cpu clocks constant) help alleviate some of the bandwidth and timing issues? Or, does overclocking the FSB not affect transfer rates between the MCH and ICH?If the latter is the case, then who will be the first manufacturer to step up with MCH/ICH bus overclocking?
Any thoughts from the anandtech folks about a follow up article, or have you already tried increasing the FSB?
Gary Key - Saturday, September 23, 2006 - link
I am working on the overclocking aspects today. I just received the final bios code so I will update the article this weekend if there is a significant change in performance when overclocking both chipsets. If not, I will comment on it in here.SixFour - Saturday, September 23, 2006 - link
Would that actually affect performance?SLIM - Saturday, September 23, 2006 - link
Probably not.Gary Key - Saturday, September 23, 2006 - link
No differences in system performance between that drive and the trusty BenQ DW1640 that it replaced.DigitalFreak - Friday, September 22, 2006 - link
If you're going to spend that much money on a Crossfire setup, why would you skimp on the motherboard? Bad idea.cmdrdredd - Friday, September 22, 2006 - link
Skimp on the motherboard? If you buy an E6400 and want to overclock you would not get a 975x board anyway. You would get a 965 board because they achiegve much much higher FSB. It's not going cheap at all, it's actually playing smart.yyrkoon - Sunday, September 24, 2006 - link
No? Thanks for telling me, and everyone else what we'd do . . . The latest ABIT 975x board is looking rather attrative, and I know I'm not alone here. Anyhow, why would I step backwards in time, for overclocking, especially when the added performance boost really isnt worth it ? Memory compatability issues ? Lack of SLI support ? I think I'll spend a little more for current technology.It's only playing it smart, if all you care about is overclocking. Alot of us who are enthuiasts, also care about stability, which means the system in question needs to be up for more than a few days. All my systems MUST be up for months at a time, and if they dont 'pass' this qualification *something* changes until they do. Its been my experience that systems pushed to the edge, often only exibit at best, a few days up time before a crash. Often times, this behavior includes mild overclocks aswell.
gersson - Friday, September 22, 2006 - link
Nah just more choices for 965 users.Quite surprising. Is there anything that's not allowing SLI to work too?
JarredWalton - Saturday, September 23, 2006 - link
In a word, NVIDIA. All they need to do is support SLI on non-NVIDIA chipsets and it would work. SiS did a driver hack a while ago for their chipset, but NVIDIA nuked that with the next driver release... and bought up SiS just for good measure.nlr_2000 - Sunday, September 24, 2006 - link
You mean ULi not SiS. ;)JarredWalton - Sunday, September 24, 2006 - link
ULi, SiS... what's the difference? LOL I knew I screwed that up. Curse the lack of edit (again)!