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
Memory Latency: No Integrated Memory Controller Necessary
One thing we pointed out in our earlier preview coverage of Intel's Core 2 Extreme is that the new processors have extremely low latency memory access, despite relying on the same memory controller as the previous generation of Intel CPUs.
Without an on-die memory controller Intel's Core 2 processor must use the memory controller in its chipset, which currently means the 128-bit DDR2 memory controller in either Intel's 965 or 975X chipset. The confusing thing is that although the Core 2 processors use the same memory controller as the old NetBurst processors, memory latency has been improved tremendously:
Intel's Core 2 processors now offer even quicker memory access than AMD's Athlon 64 X2, without resorting to an on-die memory controller. While Intel will eventually add one, the fact of the matter is that it's simply not necessary for competitive memory performance today thanks to Intel's revamped architecture. Update:As many astute readers have pointed out, Core 2's prefetchers are able to work their magic with ScienceMark 2.0, which results in the significant memory latency advantage over AMD's Athlon 64 FX-62. This advantage will not always exist; where it doesn't, AMD will continue to have lower latency memory access and where it does, Intel can gain performance advantages similar to what ScienceMark 2.0 shows.
| CPU | Everest |
CPU-Z 1.35 (8192KB, 128-byte stride) | CPU-Z 1.35 (8192KB, 64-byte stride) |
| AMD Athlon 64 FX-62 (2.8GHz) | 45.9 ns | 43.2 ns | 19.3 ns |
| Intel Core 2 Extreme X6800 (2.93GHz) | 59.8 ns | 52.8 ns | 10.9 ns |
Because of the Core 2's intelligent prefetchers doing too good of a job with ScienceMark memory latency test, we wanted to also showcase situations where Core 2 would feature slower memory accesses than the AMD platform with its integrated memory controller. Everest's results are more in line with what we'd expect to see, with the FX-62 offering over 23% faster memory accesses than the X6800. CPU-Z's latency tool also reported somewhat similar findings, with an 18% performance advantage due to AMD's integrated memory controller. CPU-Z also provided us with numbers that showcase how well Core 2 can perform if its prefetchers are able to "guess" correctly; at lower strides the Core 2 Extreme manages faster memory access than the FX-62. The 128-byte stride numbers are indicative of what will happen if the pre-fetchers are not able to get the Core 2 the data it needs, when it needs it, while the 64-byte numbers show you what can happen when things go well.
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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.