Intel's Core i7 870 & i5 750, Lynnfield: Harder, Better, Faster Stronger
by Anand Lal Shimpi on September 8, 2009 12:00 AM EST- Posted in
- CPUs
Discovery: Two Channels Aren't Worse Than Three
Intel told me something interesting when I was out in LA earlier this summer: it takes at least 3 cores to fully saturate Lynnfield's dual-channel DDR3-1333 memory bus. That's three cores all working on memory bandwidth intensive threads at the same time. That's a pretty stiff requirement. In the vast, vast majority of situations Lynnfield's dual channel DDR3 memory controller won't hurt it.
Move up to 6 or 8 core designs and a third memory channel is necessary, and that's why we'll see those processors debut exclusively on LGA-1366 platforms. In fact, X58 motherboards will only need a BIOS update to work with the 6-core 32nm Gulftown processor next year. P55 looks like it'll be limited to four cores and below.
Because of this, Lynnfield's memory bandwidth and latency cores are actually quite similar to Bloomfield. I used Everest to look at memory bandwidth and latency between a Core i7 975 and Core i7 870 (Lynnfield):
Lynnfield's memory controller is good, easily as good as what's in Bloomfield if not slightly better.
Both processors turbo'd up to 3.46GHz, indicating that Everest's memory test uses no more than two threads. The 975 ran DDR3-1066 memory (the highest it officially supports), while the 870 used DDR3-1333. The faster memory gave the 870 the advantage. Since we're not taxing all four cores, Lynnfield is at no disadvantage from a bandwidth perspective. Surprisingly enough, even SiSoft Sandra (which does use four cores for its memory bandwidth test) shows Lynnfield's dual-channel DDR3-1333 memory controller as equal to Bloomfield's triple-channel DDR3-1066 interface.
| SiSoft Sandra 2009.SP4 | Intel Core i7 975 | Intel Core i7 870 |
| Aggregate Memory Bandwidth | 17.8 GB/s | 17.3 GB/s |
Long story short? Lynnfield won't be memory bandwidth limited with DDR3-1333 for the overwhelming majority of usage cases.
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Genx87 - Tuesday, September 8, 2009 - link
But after looking at the gaming benchmarks. I am wondering if the i5 is worth the cost to upgrade from an E8400? The best I could come up with from the graphs was the Q9560@3Gz or the E8600. In most of the games they were within a few % points. Ill have to see how the i5 does with the new round of cards from AMD\Nvidia before making a decision if I am going to build a new machine or just upgrade the GPU this winter.Kaleid - Tuesday, September 8, 2009 - link
Do like I do. Buy a better GPU. I'll stick to my e8400 at least until the 32nm CPU's arrive.And according to the guru3d review overclocking makes dramatically increases power consumption during load:
"Once we overclock to 4.1 GHz... the power consumption all of a sudden is 295 Watts (!), so an additional 1200 MHz of power is costing us an additional 133 Watts."
http://www.guru3d.com/article/core-i5-750-core-i7-...">http://www.guru3d.com/article/core-i5-7...re-i7-86...
papapapapapapapababy - Tuesday, September 8, 2009 - link
"the lowest Lynnfield is a faster gaming CPU than Intel's fastest dual-core: the E8600"bullshit. the E8600 has higher minimum frame rates umm know "when it matters the most"
http://images.anandtech.com/reviews/cpu/intel/lynn...">http://images.anandtech.com/reviews/cpu/intel/lynn...
scooterlibby - Tuesday, September 8, 2009 - link
Nice review. Lynnfield seems like a great deal too for people building a new system, but from a gaming standpoint, I don't see enough performance difference to upgrade my overclocked e8400 setup. Guess it'll be Sandybridge for me!rbbot - Tuesday, September 8, 2009 - link
What is the maximum memmory you can fit onto a P55 chipset? I notice the Gigabtye board has 6 dimms but their website still says Max 16Gb?Is there a 16Gb chipset limit? Would it increase once those new high-capacity dimms from samsung make an appearance?
the machinist - Tuesday, September 8, 2009 - link
I really don't know what to make of all this. I am about to buy i7 920 and over clock it to 3.6GHZ and then sometime next year upgrade the CPU to i9 6 core on LGA 1366. SLI does not interest me... cores/threads and clock speed are my main concern for 3d rendering.Is there any reason for someone like me to get this new platform instead? Please advice me.
rsher - Tuesday, September 8, 2009 - link
I wish I had an answer for you. I am in the same situation. If you do get a good reply please post it so I could figure out what to buy..BTW what is the i9 CPU?I have some time before I need to upgrade. HAve you considered using the Xenon processors... I use MAX 2010..
rSher
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the machinist - Tuesday, September 8, 2009 - link
rSher Xeon are overkill these days considering the price premium. Single socket CPUs are so powerful these days that I just don't see the bang for the buck when it comes to Xeons. i7 920 over clocked matches some of the mid level Xeons anyway. If I was minting it and rendering only then I would get pair of high end XeonsRegarding your other question....
i9 will be 6 core version that will come out next year and you can use them on LGA1366 Mobos. I think a 8 core version will come out too. They will be expensive but by the time I decide to upgrade they should be less expensive.
PassingBy - Tuesday, September 8, 2009 - link
Can get single socket Xeon machines as well. The reason that professional users often prefer them is for ECC support. Up to you whether that matters for your applications. Naturally, for servers, ECC is the norm and that is also the situation for most professional workstations. Xeons can overclock as well, perhaps sometimes even better than the desktop equivalents, but professional users rarely overclock.Ann3x - Tuesday, September 8, 2009 - link
In some respects a great article. However the assertation that anything below the top end 1336 cpus are pointless is pretty obsurd.As others have stated the headroom and potential overclock of ANY d0 920 easily beats these new processors.
As it is, i7s are aimed at enthusiasts. FOR AN ENTHUSIAST *ie someone willing to tweak and OC* the 920 is still by fast the best bang for buck choice.
The new platform is only better if no tweeking is carried out (ie if youre not a technical user).
Therefore were left with a column aimed at technical users saying something that is only relevant to non technical users. At best its a gross simplification. As worst its missleading.
Yes, the new platform is good for the mass market, yes its exciting. However keep some perspective with your audience, the i7 920 is still BY FAR the best performance value for money CPU if you have the knowledge required to get the most out of it (as the majority of people buying X58 do).