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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JonnyDough - Tuesday, September 8, 2009 - link
Anyone who buys a $1000 CPU has more money than brains. If you wait six months you can buy a newer budget processor for about 1/15 of the cost, overclock it and obtain the same result. I would think that $925 would be more valuable to someone with sense than bragging rights for six months. I was taught that when people brag they are vain morons. A person's value should not be estimated by the stuff they have, but by the choices they make. We all get a lot in life, it's what you do with it that sets you apart. Unfortunately our society is ruled by greed and capitalism. I choose to speak against that. If you have a problem with that, I suggest you take it up with the greedy capitalist complaint department. They don't care either.max347 - Wednesday, September 9, 2009 - link
Hmm, it would seem to me that someone who has $1k to spend on a cpu probably has "alot of brains", hence the better-than-average financial position, enabling the purchase in the first place.Also, you equate greed to capitalism. This is clearly false. People get what they work for in a capitalist society. I am not saying it is perfect, though what would be a better alternative? People are not going to be financially equal, as some work harder than others. To dispute this would demonstrate a lack of experience...to say the least.
Someone chooses to get the best. It's their money, their choice. But you're right, you should probably call them a greedy capitalist.
fullcooler - Wednesday, September 9, 2009 - link
wow, you said that way calmer than I would have. very classy reply to a young leftist. perhaps when obama passes the "free $1000 cpu's for lazy punk leftists" plan, you and I can pay for his cpu,and he wont be a sellout to the man by working for it.imaheadcase - Tuesday, September 8, 2009 - link
I hate people who used that phrase "Has more money than brains". Doesn't it stand to reason, they have brains..if they have more money than you to buy the CPU... lolJNo - Tuesday, September 8, 2009 - link
Not necessarily - they might have inherited the money for example.Maybe you have more money than brains too...
JonnyDough - Tuesday, September 8, 2009 - link
Yep. These people sound like they have no idea how to be frugal with money. It's ok though, a fool and his money are soon parted.lyeoh - Thursday, September 10, 2009 - link
Stop doing that ok?If you discourage too many rich/stupid people from buying the bleeding edge stuff it just makes it harder for the rest of us.
Poor folks like me need those rich guys to rush out and buy the expensive CPUs (and GPUs etc) and work all the bugs out, get the production line ramped up etc.
Then 6-12 months later we have good and cheap stuff to buy.
The best CPU costs way less than an expensive house anyway, so it's not like he's going to cause some sort of nation wide or global financial crisis.
VaultDweller - Tuesday, September 8, 2009 - link
Maybe they don't know how to be frugal with money.Maybe they don't NEED to be frugal with money.
Sure, a fool and his money are soon parted - but so is a brilliant rich man who has more money than he needs.
niva - Tuesday, September 8, 2009 - link
I disagree with your first statement. There are people who simply want the best/fastest and will pay the money for it. Only in the last 3 or 4 years has top of the line performance become relevant only for gaming. A few years ago all sorts of pros needed the fastest they can get their hands on and purchases like $1k per CPU were actually justified.Now just because you can't afford a 1k CPU and never have been, doesn't mean people who buy such things are morons. Same goes for buying a Ferrari by the way. Quit being a jealous putz, thanks!
JonnyDough - Tuesday, September 8, 2009 - link
When you compare value ratios, yes. A $1000 CPU is soon worth about $75. A Ferrari sold as parts is worth about 1/15 of the price also. I didn't think I'd have to spell it out for you.