Intel Core Duo (Yonah) Performance Preview - Part II
by Anand Lal Shimpi on December 19, 2005 12:55 PM EST- Posted in
- CPUs
What about Clock Speeds?
Whereas the Pentium 4's extremely deep pipeline made clock-for-clock comparisons to the Athlon 64 virtually meaningless, the Pentium M and Yonah processors feature far shorter pipelines akin to AMD's architecture.
The Athlon 64 features a 12-stage integer pipeline, and while Intel has never specifically disclosed the length of Yonah's pipeline, they have made two important statements: it is longer than the Pentium III's 10-stage integer pipeline, and shorter than Conroe/Merom's 14-stage pipeline. Given the relatively tight range, Yonah's pipeline can pretty much be considered to be very similar to AMD's Athlon 64, give or take a stage of the pipeline.
The net result is that we can draw some valid conclusions based on comparisons of Yonah to the Athlon 64 X2 at similar clock speeds.
But our Yonah sample ran at 2.0GHz, which ends up being the speed of the slowest Athlon 64 X2 that is currently available: the 3800+. The highest end Athlon 64 X2s currently run at 2.4GHz, with high speeds just around the corner. So the question isn't just how competitive Yonah is at 2.0GHz, but rather, how high can Yonah go? Unfortunately, our test platform wouldn't allow us to overclock our chip very far, but thankfully, we have access to a decent amount of Intel's future roadmaps, so we can at least see what's going to happen to Yonah over the next year.
While Yonah will make its debut at a maximum speed of 2.16GHz, it will actually only receive a single speed bump before Merom's release at the end of the year. That means that we'll see a 2.33GHz Yonah after the middle of the year, but we'll have to turn to Merom to get any higher clock speeds.
Looking back to our initial articles on the Pentium M's architecture, you'll remember that one of the important aspects of its design is that all critical paths in the chip were slowed down to meet a maximum clock target. This means that Intel set a clock target for the CPU and made sure that the chip ran at that speed or below, and did not optimize any paths that would have allowed the CPU to run higher. Instead, the Pentium M team depended on the manufacturing folks to give them additional clock speed headroom by providing smaller manufacturing processes every 2 years. In other words, the Pentium M was never designed for high clock speeds, which is why it debuted at 1.5GHz and still has not even reached 2.33GHz today.
Intel's next-generation microarchitecture hopes to change that approach ever so slightly by introducing a longer pipeline into the equation, but on a much more conservative basis than the Pentium 4 did just 5 years ago. Conroe (desktop), Merom (mobile) and Woodcrest (server) will feature a 14-stage integer pipeline, which will allow for higher clock speeds than what Yonah could pull through. We would expect a debut at a minimum of 2.4GHz and probably at least one speed grade higher. Learning from their mistakes with the Pentium 4, Intel will balance the reduction in efficiency of a deeper pipeline with a wider 4-issue core (vs. the current 3-issue core used in Yonah).
So it looks like Intel's plan for 65nm is to rely on their deeper pipelined processors (Conroe/Merom/Woodcrest) for higher clock speed, with Yonah falling below the 2.5GHz mark. And based on what we've seen in the first article, a 2.33GHz Yonah would be competitive with an Athlon 64 X2 4600+, but definitely not outpacing it. This does bode well for Intel's next-generation processors, especially on the desktop with Conroe.
If the move to a 4-issue core is able to balance out the negative impact of a deeper pipeline (which admittedly it may or may not do in all cases), a higher clock speed desktop part should be very good competition for AMD's offerings. Although based on what we've seen thus far, we would be surprised if Conroe vs. Athlon 64 was a blow-out in favor of either manufacturer; more and more, it is looking like Conroe will simply bring Intel up to par with AMD, ahead in some areas, behind in others, and with the lower power advantage as long as AMD is still at 90nm.
Why the X2 and why not Turion?
One of the other questions that we were asked a lot after the first article was why we insisted on comparing a mobile Yonah processor to a desktop Athlon 64 X2, and not an AMD Turion 64. Our reasoning was obvious to some, but we felt it made sense to present it more clearly here:
Whereas the Pentium 4's extremely deep pipeline made clock-for-clock comparisons to the Athlon 64 virtually meaningless, the Pentium M and Yonah processors feature far shorter pipelines akin to AMD's architecture.
The Athlon 64 features a 12-stage integer pipeline, and while Intel has never specifically disclosed the length of Yonah's pipeline, they have made two important statements: it is longer than the Pentium III's 10-stage integer pipeline, and shorter than Conroe/Merom's 14-stage pipeline. Given the relatively tight range, Yonah's pipeline can pretty much be considered to be very similar to AMD's Athlon 64, give or take a stage of the pipeline.
The net result is that we can draw some valid conclusions based on comparisons of Yonah to the Athlon 64 X2 at similar clock speeds.
But our Yonah sample ran at 2.0GHz, which ends up being the speed of the slowest Athlon 64 X2 that is currently available: the 3800+. The highest end Athlon 64 X2s currently run at 2.4GHz, with high speeds just around the corner. So the question isn't just how competitive Yonah is at 2.0GHz, but rather, how high can Yonah go? Unfortunately, our test platform wouldn't allow us to overclock our chip very far, but thankfully, we have access to a decent amount of Intel's future roadmaps, so we can at least see what's going to happen to Yonah over the next year.
While Yonah will make its debut at a maximum speed of 2.16GHz, it will actually only receive a single speed bump before Merom's release at the end of the year. That means that we'll see a 2.33GHz Yonah after the middle of the year, but we'll have to turn to Merom to get any higher clock speeds.
Looking back to our initial articles on the Pentium M's architecture, you'll remember that one of the important aspects of its design is that all critical paths in the chip were slowed down to meet a maximum clock target. This means that Intel set a clock target for the CPU and made sure that the chip ran at that speed or below, and did not optimize any paths that would have allowed the CPU to run higher. Instead, the Pentium M team depended on the manufacturing folks to give them additional clock speed headroom by providing smaller manufacturing processes every 2 years. In other words, the Pentium M was never designed for high clock speeds, which is why it debuted at 1.5GHz and still has not even reached 2.33GHz today.
Intel's next-generation microarchitecture hopes to change that approach ever so slightly by introducing a longer pipeline into the equation, but on a much more conservative basis than the Pentium 4 did just 5 years ago. Conroe (desktop), Merom (mobile) and Woodcrest (server) will feature a 14-stage integer pipeline, which will allow for higher clock speeds than what Yonah could pull through. We would expect a debut at a minimum of 2.4GHz and probably at least one speed grade higher. Learning from their mistakes with the Pentium 4, Intel will balance the reduction in efficiency of a deeper pipeline with a wider 4-issue core (vs. the current 3-issue core used in Yonah).
So it looks like Intel's plan for 65nm is to rely on their deeper pipelined processors (Conroe/Merom/Woodcrest) for higher clock speed, with Yonah falling below the 2.5GHz mark. And based on what we've seen in the first article, a 2.33GHz Yonah would be competitive with an Athlon 64 X2 4600+, but definitely not outpacing it. This does bode well for Intel's next-generation processors, especially on the desktop with Conroe.
If the move to a 4-issue core is able to balance out the negative impact of a deeper pipeline (which admittedly it may or may not do in all cases), a higher clock speed desktop part should be very good competition for AMD's offerings. Although based on what we've seen thus far, we would be surprised if Conroe vs. Athlon 64 was a blow-out in favor of either manufacturer; more and more, it is looking like Conroe will simply bring Intel up to par with AMD, ahead in some areas, behind in others, and with the lower power advantage as long as AMD is still at 90nm.
Why the X2 and why not Turion?
One of the other questions that we were asked a lot after the first article was why we insisted on comparing a mobile Yonah processor to a desktop Athlon 64 X2, and not an AMD Turion 64. Our reasoning was obvious to some, but we felt it made sense to present it more clearly here:
- As much as Yonah is a mobile processor, it is a great indicator of the performance of Intel's future desktop processors based on the Conroe core. AMD has already stated that beyond moving to Socket-M2 and some minor updates, there will be no significant architectural changes to the Athlon 64 line next year. In other words, we know for the most part how AMD's going to be performing next year, but we have no clue how Intel will towards the end of 2006; Yonah helps us fill in the blanks.
- AMD will have a dual core Turion based mobile processor out sometime in 2006. However, it will be based on AMD's Socket-M2 platform, meaning that it will include DDR2 support. Given that we don't know exactly how DDR2 is going to impact the Athlon 64's performance, we couldn't accurately simulate the performance of AMD's upcoming dual core Turion. Comparing a dual-core Yonah to AMD's single-core Turion also wouldn't be too valid a comparison either.
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fitten - Tuesday, December 20, 2005 - link
Which should make you think about the supposed "magic" of the on-die memory controller that everyone constantly raves about as being *the* reason why the Athlon64 is as good as it is (hint: there are other reasons, the IMC is just one piece of why).
Marmion - Monday, December 19, 2005 - link
I don't get it why everyone expects a mobile chip to out-perform a desktop chip.Yonah/Core Duo is specifically a low power optimised dual core processor for laptops. Its fine to use it as an indication of the future conroe/merom, but bear in mind that these will see faster clocks, further optimisations for their specific use (desktop/mobile respectively).
Next month, Intel will have no competition for dual core laptops untill the Turion X2 comes out. Will you think that the mobile version of a desktop processor will be able to perform the same? No, because of optimisations for the all-important mobility factor (battery-life and weight).
If you want an uber-powerful desktop replacement X2 processor-powered laptop, you can do that now. But expect no battery life and an aching back or a soar arm from carrying around a 4kg+ brick. So, Intel is now offering a laptop processor, capable of performing similarly to a desktop processor, but with low power consumption, long battery life and low weight.
What am I trying to say? A Turion X2 may be slower than current Athlon X2s and yes I know 65nm vs 90nm. It probably won't be faster anyway, so Intel have a fast, efficient and cheap processor - hey you expect Turion X2 to be as cheap as the single core version?
Apples to oranges? Get over it! The Core Duo uses DDR2, AMD X2 DDR. Intel FSB, AMD Mem controller. You will never get an apples to apples comparison - its business, competition, differentiated products, call it what you like, you buy AMD, you use different RAM, different Mobos, different drivers to Intel, end of story, so its a comparison of platforms, not CPU.
*end rant*
fitten - Tuesday, December 20, 2005 - link
They don't... and that's the point and why many are impressed with Yonah... that it *does* perform favorably to a desktop platform.
Leper Messiah - Monday, December 19, 2005 - link
how do you know its going to be cheap? As far as I have seen, there are no prices released for these processors yet. And do you wanna know why we're somewhat dissapointed? Intel (and its fanbois) have been talking about how this new arc. is supposed to be the next big thing. In its current form, its not really.stateofbeasley - Monday, December 19, 2005 - link
http://www.theinquirer.net/?article=26062">http://www.theinquirer.net/?article=26062Price points are the same as the current platform.
Yonah is not NGMA. Yonah is a P6 family processor.
People must read the news before they post!!!!
coldpower27 - Monday, December 19, 2005 - link
This isn't really new architecture, the next big thing is supposed to be Intel's NGMA, where alot of changes are going to be made.KayKay - Monday, December 19, 2005 - link
I am an AMD fanboybut the results (power consumption esp.) are very impressive
guess intel wants to keep things competitive
hope amd ups the ante in response
eetnoyer - Monday, December 19, 2005 - link
With AMD announcing the use of SiGe in processors coming up very soon, it looks like they could still get a decent drop in power consumption at 90nm. I'd guess that's what they're waiting for to release the Turion x2. I doubt that it will be quite enough to match the power consumption of Yonah, but should mostly suffice until the 65nm shrink. It will also apparently serve to greatly reduce the area required for L2 cache by shrinking the cells. Once that happens I imagine that AMD will hold a small power/performance lead over Merom/Conroe/Woodcrest since adding 64 bit will tend to up their power consumption somewhat. At that point, AMD will be using SOI and SiGe, while Intel will only be using SiGe.As for continuing the ramp of frequencies, I don't think that it's going to play a hugely significant role going forward. That's why everyone is going multi-core these days. It looks like rough performance parity is here to stay between the two. What I think AMD is aiming at is a duopoly in the CPU market. That is the point of the lawsuit, and the greatly expanding capacity that AMD is targeting (Fab36, Chartered, Fab38, etc...). What Intel really needs to worry about is AMD's ability to increase their brand awareness and supply large vendors reliably. Once that happens, Intel will need to compete on price. While AMD is very comfortable living on $100 ASP, that would be catastrophic to Intel's bottom line. I think over the next few years (barring any catastrophic screw-ups by AMD) we are going to see alot of cost-cutting at Intel.
Sorry for the off-topic ramblings, but I tend to look at things from an investors' POV.
Leper Messiah - Monday, December 19, 2005 - link
So I guess the biggest question for these (at least to me, since I don't have a need for an uber-lappy) is price and a converter for a mobo, and I guess OC-abilty. If they can match clock speeds of the x2s (2.6GHz+) and come out to be cheaper, then I might consider buying one of these, but I don't see AMD's desktop market being threatened, considering Intel's last gasps with netburst (let it die already!).If AMD can milk another 400MHz or so out of its K8 arctechture in its current form, they'll stay competitive with mermom it seems to me. Yonah certainly isn't the AMD killer the intel fanboi's have been heralding it as though.
fitten - Tuesday, December 20, 2005 - link
I've seen a number of "reports" of these Yonahs (Core Duo) hitting 2.5GHz quite easily without even raising the voltage. It's "as if" it were designed to run in the 2.5-2.6GHz range but not released that way... yet.