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
Lynnfield's Un-Core: Faster Than Most Bloomfields
A few years ago I had a bet going with AMD's Ian McNaughton. We were at an AMD event where the Phenom architecture was first being introduced and he insisted that the L3 cache was part of the memory controller. This didn't make any sense to me so I disagreed. Minutes later a presentation slide went up on a projector talking about how the L3 cache and memory controller were on the same voltage plane; that's what he meant. Ian laughed a lot and to this day he holds it over my head.
The moral of the story is in Phenom and later in Nehalem, the processor is divided into two parts. Intel named them the core and the un-core. The "core" of these multi-core processors is made up of each individual processor core and its associated private caches (L1/L2). The "uncore" refers to everything else: PCIe controller, memory controller, DMI/QPI and the L3 cache.
The uncore isn't as critical for performance but is made up of a ton of transistors; roughly 400 million in the case of Lynnfield/Bloomfield (more if you count the PCIe controller). In order to save power, Intel uses slower transistors that have lower leakage for the un-core. As a result, the un-core can't clock up as high as the core and runs at a lower multiplier.
Take the Bloomfield Core i7 975 for example. The core runs at 25x BCLK (25 x 133MHz = 3.33GHz), but the un-core runs at 20x BCLK (20 x 133MHz = 2.66GHz). The rest of the chips, including Lynnfield, have slower un-cores:
| CPU | Socket | Core Clock | Un-Core Clock |
| Intel Core i7 975 Extreme | LGA-1366 | 3.33GHz | 2.66GHz |
| Intel Core i7 965 Extreme | LGA-1366 | 3.20GHz | 2.66GHz |
| Intel Core i7 950 | LGA-1366 | 3.06GHz | 2.13GHz |
| Intel Core i7 940 | LGA-1366 | 2.93GHz | 2.13GHz |
| Intel Core i7 920 | LGA-1366 | 2.66GHz | 2.13GHz |
| Intel Core i7 870 | LGA-1156 | 2.93GHz | 2.40GHz |
| Intel Core i7 860 | LGA-1156 | 2.80GHz | 2.40GHz |
| Intel Core i5 750 | LGA-1156 | 2.66GHz | 2.13GHz |
Here's another area where Lynnfield is better than the lower end Bloomfields: its uncore runs at 2.40GHz instead of 2.13GHz. The exception being the Core i5 750, its uncore is stuck at 2.13GHz as well. Once again, only the "Extreme" Bloomfields have a faster uncore.
Lynnfield's Memory Controller: Also Faster than Bloomfield
Intel only officially supports two memory speeds on Bloomfield: DDR3-800 and DDR3-1066. Obviously we're able to run it much faster than that, but this is what's officially validated and supported on the processors.
Lynnfield is a year newer and thus gets a tweaked memory controller. The result? Official DDR3-1333 support.
Three Lynnfield memory kits (left to right): OCZ, Patriot and Kingston
The same sort of rules apply to Lynnfield memory kits that we saw with Bloomfield. You don't want to go above 1.65V and thus all the kits we've seen run at 1.5V for the stock JEDEC speeds or 1.65V for the overclocked modules.
Like Bloomfield, 1.65V is the max we'll see on Lynnfield
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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.