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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bob661 - Friday, July 14, 2006 - link
But they're not available today. Why is that?So Intel is launching this twice? What is going on today? Technology preview?
Questar - Friday, July 14, 2006 - link
Sold out?
RTFA. The NDA lifted today. Launch is on the 27th.
bob661 - Friday, July 14, 2006 - link
If they were sold out they would still show on Newegg and ZZF.I RFTA! That's how I was able to correlate the lack of product to the availability of benchmarks. Products leak all of the time and NDA's are held in place. This maybe a creative way of paper launching but it's still a paper launch.
Questar - Friday, July 14, 2006 - link
Yeah, because that's the only two places you buy a CPU from.
Sheesh.
Questar - Friday, July 14, 2006 - link
bob and MrKaz, forever the fanboy.Please explain to me why Intel having the better cpu upsets you so?
MrKaz - Monday, July 17, 2006 - link
And you?It can be better than Cyrix, IBM, Sun, ... I don’t care.
But you seem to care more than me.
If you don’t, why do you complain?
This is not for me because my maximum 100€ for processor.
It’s cheap (compared to others Intel past released brand new CPU) but not cheap enough.
bob661 - Friday, July 14, 2006 - link
I'm not a fanboi. I just hate hypocrites. If you read another post of mine in this section (use the scroll button Luke) you will see me praise the performance of the Conroe. I plan on buying one for my wife. I'll probably get a K8L if it turns out to be even or faster than Conroe otherwise I'll get a Conroe for myself.bob661 - Friday, July 14, 2006 - link
Here's the post I made. Sound like a fanboi to you?forPPP - Friday, July 14, 2006 - link
Why buying more expensive and slower Core 2 Extreme (X6800, 2.93 GHz) ? There is cheaper Woodcrest at 3.0 GHz !Are there no motherboard with unbuffered memory support for Woodcrest ?
coldpower27 - Friday, July 14, 2006 - link
Nope Intel doesn't allow their Server processor to be used for desktop stuff as it's LGA771 socket.