Intel's Pentium Extreme Edition 955: 65nm, 4 threads and 376M transistors
by Anand Lal Shimpi on December 30, 2005 11:36 AM EST- Posted in
- CPUs
Literally Dual Core
One of the major changes with Presler is that unlike Smithfield, the two cores are not a part of the same piece of silicon. Instead, you actually have a single chip with two separate die on it. By splitting the die in two, Intel can reduce total failure rates and even be far more flexible with their manufacturing (since one Presler chip is nothing more than two Cedar Mill cores on a single package).
In order to find out if there was an appreciable increase in core-to-core communication latency, we used a tool called Cache2Cache, which Johan first used in his series on multi-core processors. Johan's description of the utility follows:
Not only did we not find an increase in latency between the two cores on Presler, communication actually occurs faster than on Smithfield. We made sure that it had nothing to do with the faster FSB by clocking the chip at 2.8GHz with an 800MHz FSB and repeated the tests only to find consistent results.
We're not sure why, but core-to-core communication is faster on Presler than on Smithfield. That being said, a difference of less than 9ns just isn't going to be noticeable in the real world - given that we've already seen that the Athlon 64 X2's 100ns latency doesn't really help it scale better when going from one to two cores.
One of the major changes with Presler is that unlike Smithfield, the two cores are not a part of the same piece of silicon. Instead, you actually have a single chip with two separate die on it. By splitting the die in two, Intel can reduce total failure rates and even be far more flexible with their manufacturing (since one Presler chip is nothing more than two Cedar Mill cores on a single package).
The chip at the bottom of the image is Presler; note the two individual cores.
In order to find out if there was an appreciable increase in core-to-core communication latency, we used a tool called Cache2Cache, which Johan first used in his series on multi-core processors. Johan's description of the utility follows:
"Michael S. started this extremely interesting thread at the Ace's hardware Technical forum. The result was a little program coded by Michael S. himself, which could measure the latency of cache-to-cache data transfer between two cores or CPUs. In his own words: "it is a tool for comparison of the relative merits of different dual-cores."Armed with Cache2Cache, we looked at the added latency seen by Presler over Smithfield:
"Cache2Cache measures the propagation time from a store by one processor to a load by the other processor. The results that we publish are approximately twice the propagation time. For those interested, the source code is available here."
| Cache2Cache Latency in ns (Lower is Better) | |
| AMD Athlon 64 X2 4800+ | 101 |
| Intel Smithfield 2.8GHz | 253.1 |
| Intel Presler 2.8GHz | 244.2 |
Not only did we not find an increase in latency between the two cores on Presler, communication actually occurs faster than on Smithfield. We made sure that it had nothing to do with the faster FSB by clocking the chip at 2.8GHz with an 800MHz FSB and repeated the tests only to find consistent results.
We're not sure why, but core-to-core communication is faster on Presler than on Smithfield. That being said, a difference of less than 9ns just isn't going to be noticeable in the real world - given that we've already seen that the Athlon 64 X2's 100ns latency doesn't really help it scale better when going from one to two cores.
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Aenslead - Saturday, December 31, 2005 - link
As J.J., from Spider-Man would say:"Ceap, crap, mega-crap!" and then toss it away.
ElJefe - Saturday, December 31, 2005 - link
well it does move very fast in games. that is nice to see finally.it would be great if the overall power draw numbers were shown as on tomshardware. even there they showed a 90 watt difference between 4800 and the new 65nm. and that wasnt on the oc'd one. The oc'd one showed 150 more watts draw.
Viditor - Saturday, December 31, 2005 - link
Agreed...if it weren't for the X2, this would be an excellent chip by comparison!
Betwon - Friday, December 30, 2005 - link
Now, anandtech begin to learn the truth. There are still many knowledge about CPU that anandtech need to learn.The resluts of tests are simple and clear, but the reasons are complex.
In past years, anandtech took many mistakes about the correct reasons.
bldckstark - Monday, January 2, 2006 - link
You do realize that none of this stuff is very important, right? Both chips work well. Nobody should be criticized for buying either one of them.I love my FIVE computers but making sure my wife and kids are healthy and happy is way more important than any electronic device, especially just one piece of it.
Your damaging and hostile statements are making it appear as if you have forgotten this and the most important thing in the world is that you make all of us geeks think Anandtech is not perfect. News update - WE ALL KNOW THAT! We still like it.
bob4432 - Friday, December 30, 2005 - link
why don't you do the gaming benchmark with bf2 fps unlocked? it appears that it is just hitting its built in lock with both the fx-57 and also P955 EE 3.46 cpus.Spacecomber - Friday, December 30, 2005 - link
I believe that they are using the timedemo feature of the game and that the frame rate max doesn't affect this. It would be nice to see more than just average frame rates reported for games, though. At least a range should be mentioned and maybe a standard deviation.Space
Betwon - Friday, December 30, 2005 - link
We see a test, where the average fps of PD is less than (about 1% - 2%) the fps of AMD's. But PD's fps is more stable than AMD's.In the case that the average fps of netburst is better than the average fps of K8, the test shows that netburst is more stable than K8.
Betwon - Friday, December 30, 2005 - link
The test isn't bf2.bob4432 - Friday, December 30, 2005 - link
any link you could give me on how to do the time demo from within bf2? is this new with the 1.12 patch?thanks