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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Ben90 - Tuesday, September 8, 2009 - link
Was reading it pretty casually thinking it was just a preview because i didnt think the NDA lifted yet.... then i saw a next page... looked at the tab and it has like 20 pages OMGOMGOMGOMG!!! ITS OUT LOL....Im gonna try really really hard to read the article before i go to the gaming performance though...prolly wont make itLashek - Wednesday, September 9, 2009 - link
you compare it to the Q6600 a lot in the text, but no comparison with an overclocked Q6600 is made in the benches...If you have figures of an overclocked Q6600, could you add them? all over the web these question are asked but business leaders who own these web sites dont want to challenge a overclocked core 2 duo,and quads,or is it politics?
coldpower27 - Thursday, September 10, 2009 - link
You will have to compare an overclocked I750 or i860 to the Q6600 as that would only be fair, no sense doing a stock vs overclocked comparison.It is well known you can equal todays stock performance by overclocking to some degree, but if your going to compare overclock then you need to overclock both processors.
Q6600 will be destroyed by i750 and i860 if you compare perf/watt however.
Joshaze - Wednesday, September 9, 2009 - link
Anand,When testing World of Warcraft what processAffinityMask value where you using?
The default value for this variable does not take advantage of all cores on the Core i7 processors.
Here is the article discussing the CVAR: http://forums.worldofwarcraft.com/thread.html?topi...">http://forums.worldofwarcraft.com/thread.html?topi...
The value should be 255 for 8 cores and 15 for 4 cores.
If not, any chance you could retest using the above values and report back on any changes?
Googer - Wednesday, September 9, 2009 - link
The lack of PS2 is a real deal killer for me, I have a beloved IBM Clicky Model M keyboard (1391401) and I will not give it up for anything. I know PS2-usb keyboard adapter exist but they just don't work very well.I am not alone, there are tens of thousands of vintage keyboard lovers out there and the IBM Model 1391401 is one of the more popular ones among keyboard aficionados.
Kind of sad that a 20-30 year old keyboard still works as well as they day it was made, new cheaper keyboards are less acuurate, uncomfortable, very flimsy and are poorly made. You would be lucky to get 5-6 years out of 'some' of these newer $90+ keyboards.
Save PS2, keep it alive. PS/2 has less lag than any USB keyboard I have tried. There are a lot of great keyboards still in use. There is no shortage of real estate on the back IO shields, so there should be no reason not to include a PS/2 port..
MamiyaOtaru - Thursday, September 10, 2009 - link
Seconding this. USB is incapable of providing n-key rollover for keyboards. PS2 can. Not everyone needs that, but I won't do without it.Zoomer - Wednesday, September 9, 2009 - link
I saw at least one PS2 port on these motherboards. What are you talking about again? Yes, they seem to be shared with the PS2 port for mice, but mice work the same on USB anyway.Taft12 - Wednesday, September 9, 2009 - link
This is probably the most off-topic post I've seen on this site. Fortunately for all of us, your rant is invalid and you never have to say anything about this ever again:http://www.syba.com/index.php?controller=Product&a...">http://www.syba.com/index.php?controller=Product&a...
boogerlad - Tuesday, September 8, 2009 - link
where't ta152h now? That idiot is finally done trolling.snakeoil - Wednesday, September 9, 2009 - link
all the results of this review are biased because they were made with turbo enabled, that's at least 600 mhz overclocking.to be fair you must compare this results against a phenom 2 overclockded at least 600 mhz
people is not stupid.