The Lynnfield Preview: Rumblings of Revenge
by Anand Lal Shimpi on May 29, 2009 1:00 PM EST- Posted in
- CPUs
Lynnfield’s Secret? Turbo Mode
The current Core i7 runs at a multiple of its BCLK, which is 133MHz. The Core i7-920 runs at 20x BCLK (2.66GHz) while the i7-965 runs at 24x BCLK (3.2GHz). If the chip isn’t running anywhere near its max TDP, the i7 will overclock itself by one speed bin (133MHz). Now say you’re running a single-threaded application that’s got only one core active, if the chip is cool enough the i7 will overclock itself by two speed bins (266MHz).
Turbo mode on the i7 works well and as I found is generally responsible for a 3 - 4% increase in performance. Despite its benefits, the i7’s Turbo mode is very conservative. Our own overclocking tests show that i7s have no problems running at up to 3.8GHz without any additional cooling or voltage, even with all four cores under full load. Given that it was Intel’s first Nehalem architecture, I can understand the hesitation not to go crazy with turbo.
The second version of Intel’s Nehalem turbo mode came with the high end Nehalem Xeon processors. While the single-socket processors worked just like the desktop i7s, the higher end dual-socket Xeons can turbo up more aggressively.
The Xeon E5520, E5530 and E5540 can all boost their clocks by one bin if 3 or 4 cores are active, but two bins if 1 or 2 are active. The X5000 series gets even more aggressive; with 3 or 4 cores active the chips can overclock themselves by up to 266MHz, and if 1 or 2 cores are active they can turbo up an additional 400MHz.
Lynnfield marks Intel’s third generation Nehalem turbo and is correspondingly more awesome.
The leaked roadmaps show that the two higher end Lynnfields can turbo up to five bins, or 667MHz while the entry level Lynnfield can turbo up to four bins (533MHz). I’m guessing this is for a single active core, but what about when more than one core is active? The table below has the turbo specs for the Xeon X5570 (95W TDP), the Core i7-940 (130W TDP) and my guesstimates for the 2.93GHz Lynnfield (95W TDP):
| Processor | Clock Speed | Max Turbo | |||
| 4 Cores Active | 3 Cores Active | 2 Cores Active | 1 Core Active | ||
| Intel Xeon X5570 | 2.93GHz | 3.2GHz | 3.2GHz | 3.33GHz | 3.33GHz |
| Intel Core i7-940 | 2.93GHz | 3.06GHz | 3.06GHz | 3.06GHz | 3.2GHz |
| Intel Lynnfield ESTIMATE | 2.93GHz | 3.2GHz | 3.2GHz | 3.60GHz | 3.60GHz |
Given the similarity in clock speed and TDP to Intel's Xeon X5570, I'm guessing the 2.93GHz Lynnfield will follow the same 2/2/3/3 turbo pattern as the Xeon. The higher max turbo frequency means that we'll at least see 3.60GHz with only 1 core active and I'm not really sure what will happen if two cores are active; if Intel follows the Xeon pattern then we'll see 3.6GHz as well, but we may very well see 3.33GHz or 3.46GHz instead when only two cores are active.
Either way a quad-core Lynnfield, thanks to its aggressive turbo mode, will end up delivering good performance regardless of the number of concurrent threads. Forget about it being a quad-core CPU and just think of it as a CPU that will perform as best as possible given its 95W thermal envelope. This, my friends, is the future of multi-core processors. It doesn't matter how many cores you have, just view them as execution resources; if you only need two powerful cores, that's what you get, and if you need to run 8 threads then that's what you'll get. Imagine what we'll get on the 4th or 5th generation of turbo modes.
To those who are wondering why Lynnfield even makes sense, I believe its turbo mode will be its saving grace. I'm more puzzled by the i7-920 at this point.
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Anand Lal Shimpi - Saturday, May 30, 2009 - link
P55 essentially has the same ICH feature set as P45. You get support for six SATA 3.0Gb/s ports, 12 USB 2.0 and PCIe 2.0.Intel's chipsets are actually what I use for all of my SSD tests and they work quite well. I wouldn't expect any different out of P55.
Remember that P55 is only the first Lynnfield chipsets, next year we'll see more. This chart speculates on some of the features of those (it also lists 14 USB instead of 12, I'm not sure which one is right):
http://img405.imageshack.us/img405/74/hkepcibexpea...">http://img405.imageshack.us/img405/74/hkepcibexpea...
Take care,
Anand
Drazick - Saturday, May 30, 2009 - link
I thought so...I hope someone will adopt the changes quickly.
It's about time to get rid of the BIOS and make room for speed improvements int the Flash chips (Both via the SATA 3 and USB 3).
Do you see in the horizon how long will it take before will see those features?
Thank you for the response.
Krogoth255 - Saturday, May 30, 2009 - link
I find it very funny when people make a huge fuss over a 2-10% difference in performance (i5 versus i7). It is sad that even budget CPUs are bloody overkill for majority of computer users.The bottom line is that i5 is going to be Intel's next big winner. It is the perfect Phenom II killer and an excellent successor to the Core 2 parts that it is replacing. I7 makes very little sense unless time is $$$$$.
PrinceGaz - Sunday, May 31, 2009 - link
Exactly. My nearly four-year old S939 Athlon 64 X2 still performs everything I do (with one exception) more than fast enough so the difference between the i5 and i7 would be irrelevant. I still think I'm at least a year or two from doing a new build (the only thing of any value at all in my current box I could reuse would be the graphics-card, a 640MB 8800GTS; most of the drives are parallel ATA, and the memory is of course DDR).Given that the one app where my current rig struggles is PCSX2 (a Playstation 2 emulator), it seems kind of silly to spend upwards of £500 for a new box simply to play PS2 console games, when I could probably buy a new PS2 console for under £100. Therefore debates over the relative merits of i5 and i7 which are both much faster are rather moot for me at the moment, and the vast majority of the PC buying public. It is nice to know how they compare though, and what their pros and cons are (the main con I see being the price of X58 mobos), so I'm thankful for this informative article on AT.
just4U - Saturday, May 30, 2009 - link
I don't quite understand why X58 boards are so expensive. At first we were complaining about ddr3 prices.. but they've come down to a managable point. While cheaper X58 solutions are starting to crop up it's still extremely high and I don't quite get why that is.With the memory controller integrated into the chip you'd think that the cost of the boards would be cheaper overall. That was one of Amd's main selling points (if I remember right) but for the i7 not the case.. the boards are priced incredibly high.
Anand Lal Shimpi - Saturday, May 30, 2009 - link
It's artificial. The boards are priced so high because Intel charges quite a bit of money for the X58 chipset. It's the cost of competition; if AMD had a true answer to i7 we'd have much more affordable i7 platforms all of the sudden :)Take care,
Anand
jmurbank - Sunday, May 31, 2009 - link
Chipset and processor prices are two different things. Neither are related to each other. Like all products, prices of chipsets is related to other chipsets competing at the same level. Since the X58 does not have any competitor, people have to pay a high premium for a complete i7 system. If nVidia is allowed to make a chipset for the i7 processor, we will see these high premium prices decrease. Since the i7 processor is designated as enthusiast setup, prices will still be at enthusiast pricing.just4U - Saturday, May 30, 2009 - link
You've had them on your test beds so you'd know better then I. Hell I haven't even gotten any hands on with the i7 since people here keep opting for the PII. Not that that's a bad thing, I am rather impressed with those overall just..Im beginning to realize the only way Im going to get my grubby little paws on a I7 is if I go out and build it for myself. Even I balk a little bit at the price tag of some of those boards but there are a few coming down the pipeline that look a little bit more reasonably priced.
Jabbernyx - Saturday, May 30, 2009 - link
EX58-UD3R = $150 from eWiz ;)goinginstyle - Saturday, May 30, 2009 - link
It is $185.99 at eWiz with a $15 rebate that will take two months to get for an end price of $170.99.