Intel's Core 2 Extreme & Core 2 Duo: The Empire Strikes Back
by Anand Lal Shimpi on July 14, 2006 12:00 AM EST- Posted in
- CPUs
FSB Bottlenecks: Is 1333MHz Necessary?
Although all desktop Core 2 processors currently feature a 1066MHz FSB, Intel's first Woodcrest processors (the server version of Conroe) offer 1333MHz FSB support. Intel doesn't currently have a desktop chipset with support for the 1333MHz FSB, but the question we wanted answered was whether or not the faster FSB made a difference.
We took our unlocked Core 2 Extreme X6800 and ran it at 2.66GHz using two different settings: 266MHz x 10 and 333MHz x 8; the former corresponds to a 1066MHz FSB and is the same setting that the E6700 runs at, while the latter uses a 1333MHz FSB. The 1333MHz setting used a slightly faster memory bus (DDR2-811 vs. DDR2-800) but given that the processor is not memory bandwidth limited even at DDR2-667 the difference between memory speeds is negligible.
With Intel pulling in the embargo date of all Core 2 benchmarks we had to cut our investigation a bit short, so we're not able to bring you the full suite of benchmarks here to investigate the impact of FSB frequency. That being said, we chose those that would be most representative of the rest.
Why does this 1333MHz vs. 1066MHz debate even matter? For starters, Core 2 Extreme owners will have the option of choosing since they can always just drop their multiplier and run at a higher FSB without overclocking their CPUs (if they so desire). There's also rumor that Apple's first Core 2 based desktops may end up using Woodcrest and not Conroe, which would mean that the 1333MHz FSB would see the light of day on some desktops sooner rather than later.
The final reason this comparison matters is because in reality, Intel's Core architecture is more data hungry than any previous Intel desktop architecture and thus should, in theory, be dependent on a nice and fast FSB. At the same time, thanks to a well engineered shared L2 cache, FSB traffic has been reduced on Core 2 processors. So which wins the battle: the data hungry 4-issue core or the efficient shared L2 cache? Let's find out.
On average at 2.66GHz, the 1333MHz FSB increases performance by 2.4%, but some applications can see an even larger increase in performance. Under DivX, the performance boost was almost as high as going from a 2MB L2 to a 4MB L2. Also remember that as clock speed goes up, the dependence on a faster FSB will also go up.
Thanks to the shared L2 cache, core to core traffic is no longer benefitted by a faster FSB so the improvements we're seeing here are simply due to how data hungry the new architecture is. With its wider front end and more aggressive pre-fetchers, it's no surprise that the Core 2 processors benefit from the 1333MHz FSB. The benefit will increase even more as the first quad core desktop CPUs are introduced. The only question that remains is how long before we see CPUs and motherboards with official 1333MHz FSB support?
If Apple does indeed use a 1333MHz Woodcrest for its new line of Intel based Macs, running Windows it may be the first time that an Apple system will be faster out of the box than an equivalently configured, non-overclocked PC. There's an interesting marketing angle.
Facebook
Twitter
RSS
202 Comments
View All Comments
Calin - Friday, July 14, 2006 - link
A very good part of what Intel makes (processor wise) goes to mainstream and lower-than-mainstream performance (Celeron-like chips). There might be, in the end (of the year), enough production of Core2 to fill the enthusiast/retail market.Indeed, the Netburst are obsolete over night...
xFlankerx - Friday, July 14, 2006 - link
Not just Netburst, even the Athlon 64s are obsolete now.With the Pentium 4 vs. Athlon 64 debate, atleast there were moments when going with the Pentium 4 could be justified. However, because of the huge difference in performance and prices of the Core 2 Duo and Athlon 64 processors, I think it would be foolish to go for a new Athlon 64 system right now (unless ofcourse you're on a tight budget).
Calin - Friday, July 14, 2006 - link
Yes, Pentium4 was better in so-called media benchmarks, and there were some uber-optimized application that were flying on Pentium4.Right now, there are (as stated in article) three competitors: Core2Duo at high price, performance and low power, Athlon64 X2 at lower price, performance and a bit higher power, and PentiumD at dumping prices, even lower performance and quite a bit higher power. It all depends on how much money you would invest.
I am thinking at a single core Core2, and integrated video mainboard with ATI or NVidia chipset - or a Sempron AM2 3000+. I wonder how cheap a Core2 Solo would be
Squidward - Friday, July 14, 2006 - link
Agreed, an excellent review, I loved Anand's anologies about the dinner table. I get the feeling he may have been thinking Arby's (tm) when he wrote this review. :)My goodness does Intel's new lineup impress. I've been using AMD ever since the K6/2 days and was planning on getting an X2 soon, but this review has made me decide to wait it out just a little bit longer.
Great article guys, keep up the good work.
Viditor - Friday, July 14, 2006 - link
I'd say that the A64 X2s are still quite competitive, depending on your budget and availability of the C2Ds.
That said, Intel has done a magnificent job with these chips!
It looks like Conroe will own the high end market until AMD can release K8L...but judging by the review, AMD will own the low end. I can't see anyone buying a PD once AMD drops the prices, nor can I see anyone buying an AMD if they can afford a medium or higher priced system.
jkostans - Friday, July 14, 2006 - link
With the 1.83GHz conroe at $183 and on par with a X2 4600, I don't see the low end going for AMD either.Ultra low end will be a toss up however.Viditor - Saturday, July 15, 2006 - link
If you look at the situation in total, it will probably make more sense...
1. The X2 has far more inexpensive but fully functional motherboards to choose from.
2. Supply will be far more constrained on the Conroe than on the X2
Combos are king in the low end...for example, if you combine an Asus M2NPV-VM with an AM2 X2 3800 (after the price drop), you get a good dual core system with Raid 5, HDTV, nVidia 6150 graphics, Firewire, dual screen (VGA and DVI), and just about every whistle and bell you could want for (est) ~$250. You'd be hard pressed to find just a Conroe-ready motherboard with that kind of functionality for that kind of money (let alone a combo).
duploxxx - Friday, July 14, 2006 - link
correct the real performance king will be for now the conroe starting from 6600 and above. maybe 6400 this will be clear later. but for the budget platform it will be better to buy an x2 3800 or 4200 seeing the price combo it will have. mobo + proc is way cheaper then any intel combo (100$ and more) thats a lot for a budget system.duploxxx - Friday, July 14, 2006 - link
oh and one big item which is left out of sighht... the performance gain is less on a conroe then on a k8.. its a difference of 15% in identical apps... that's an interesting point for the future... just my opinionXenoid - Friday, July 14, 2006 - link
Yes it was a very, very well done review and I will definitely be purchasing one of these bad boys.