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
Multi-GPU SLI/CF Scaling: Lynnfield's Blemish
When running in single-GPU mode, the on-die PCIe controller maintains a full x16 connection to your graphics card:
Hooray.
In multi-GPU mode, the 16 lanes have to be split in two:
To support this the motherboard maker needs to put down ~$3 worth of PCIe switches:
Now SLI and Crossfire can work, although the motherboard maker also needs to pay NVIDIA a few dollars to legally make SLI work.
The question is do you give up any performance when going with Lynnfield's 2 x8 implementation vs. Bloomfield/X58's 2 x16 PCIe configuration? In short, at the high end, yes.
I looked at scaling in two games that scaled the best with multiple GPUs: Crysis Warhead and FarCry 2. I ran all settings at their max, resolution at 2560 x 1600 but with no AA.
I included two multi-GPU configurations. A pair of GeForce GTX 275s from EVGA for NVIDIA:
A coupla GPUs and a few cores can go a long way
And to really stress things, I looked at two Radeon HD 4870 X2s from Sapphire. Note that each card has two GPUs so this is actually a 4-GPU configuration, enough to really stress a PCIe x8 interface.
First, the dual-GPU results from NVIDIA.
| NVIDIA GeForce GTX 275 | Crysis Warhead (ambush) | Crysis Warhead (avalanche) | Crysis Warhead (frost) | FarCry 2 Playback Demo Action |
| Intel Core i7 975 (X58) - 1GPU | 20.8 fps | 23.0 fps | 21.4 fps | 41.0 fps |
| Intel Core i7 870 (P55) 1GPU | 20.8 fps | 22.9 fps | 21.5 fps | 40.5 fps |
| Intel Core i7 975 (X58) - 2GPUs | 38.4 fps | 42.3 fps | 38.0 fps | 73.2 fps |
| Intel Core i7 870 (P55) 2GPUs | 38.0 fps | 41.9 fps | 37.4 fps | 65.9 fps |
The important data is in the next table. What you're looking at here is the % speedup from one to two GPUs on X58 vs. P55. In theory, X58 should have higher percentages because each GPU gets 16 PCIe lanes while Lynnfield only provides 8 per GPU.
| GTX 275 -> GTX 275 SLI Scaling | Crysis Warhead (ambush) | Crysis Warhead (avalanche) | Crysis Warhead (frost) | FarCry 2 Playback Demo Action |
| Intel Core i7 975 (X58) | 84.6% | 83.9% | 77.6% | 78.5% |
| Intel Core i7 870 (P55) | 82.7% | 83.0% | 74.0% | 62.7% |
For the most part, the X58 platform was only a couple of percent better in scaling. That changes with the Far Cry 2 results where X58 manages to get 78% scaling while P55 only delivers 62%. It's clearly not the most common case, but it can happen. If you're going to be building a high-end dual-GPU setup, X58 is probably worth it.
Next, the quad-GPU results from AMD:
| AMD Radeon HD 4870 X2 | Crysis Warhead (ambush) | Crysis Warhead (avalanche) | Crysis Warhead (frost) | FarCry 2 Playback Demo Action |
| Intel Core i7 975 (X58) - 2GPUs | 25.8 fps | 31.3 fps | 27.0 fps | 70.9 fps |
| Intel Core i7 870 (P55) 2GPUs | 24.4 fps | 31.1 fps | 26.6 fps | 71.4 fps |
| Intel Core i7 975 (X58) - 4GPUs | 27.0 fps | 57.4 fps | 47.9 fps | 117.9 fps |
| Intel Core i7 870 (P55) 4GPUs | 24.2 fps | 50.0 fps | 36.5 fps | 116 fps |
Again, what we really care about is the scaling. Note how single GPU performance is identical between Bloomfield/Lynnfield, but multi-GPU performance is noticeably lower on Lynnfield. This isn't going to be good:
| 4870 X2 -> 4870 X2 CF Scaling | Crysis Warhead (ambush) | Crysis Warhead (avalanche) | Crysis Warhead (frost) | FarCry 2 Playback Demo Action |
| Intel Core i7 975 (X58) | 4.7% | 83.4% | 77.4% | 66.3% |
| Intel Core i7 870 (P55) | -1.0% | 60.8% | 37.2% | 62.5% |
Ouch. Maybe Lynnfield is human after all. Almost across the board the quad-GPU results significantly favor X58. It makes sense given how data hungry these GPUs are. Again, the conclusion here is that for a high end multi-GPU setup you'll want to go with X58/Bloomfield.
A Quick Look at GPU Limited Gaming
With all of our CPU reviews we try to strike a balance between CPU and GPU limited game tests in order to show which CPU is truly faster at running game code. In fact all of our CPU tests are designed to figure out which CPUs are best at a number of tasks.
However, the vast majority of games today will be limited by whatever graphics card you have in your system. The performance differences we talked about a earlier will all but disappear in these scenarios. Allow me to present data from Crysis Warhead running at 2560 x 1600 with maximum quality settings:
| NVIDIA GeForce GTX 275 | Crysis Warhead (ambush) | Crysis Warhead (avalanche) | Crysis Warhead (frost) |
| Intel Core i7 975 | 20.8 fps | 23.0 fps | 21.4 fps |
| Intel Core i7 870 | 20.8 fps | 22.9 fps | 21.5 fps |
| AMD Phenom II X4 965 BE | 20.9 fps | 23.0 fps | 21.5 fps |
They're all the same. This shouldn't come as a surprise to anyone, it's always been the case. Any CPU near the high end, when faced with the same GPU bottleneck, will perform the same in game.
Now that doesn't mean you should ignore performance data and buy a slower CPU. You always want to purchase the best performing CPU you can at any given pricepoint. It'll ensure that regardless of the CPU/GPU balance in applications and games that you're always left with the best performance possible.
The Test
| Motherboard: | Intel DP55KG (Intel P55) Intel DX58SO (Intel X58) Intel DX48BT2 (Intel X48) Gigabyte GA-MA790FXT-UD5P (790FX) |
| Chipset: | Intel X48 Intel X58 Intel P55 AMD 790FX |
| Chipset Drivers: | Intel 9.1.1.1015 (Intel) AMD Catalyst 9.8 |
| Hard Disk: | Intel X25-M SSD (80GB) |
| Memory: | Qimonda DDR3-1066 4 x 1GB (7-7-7-20) Corsair DDR3-1333 4 x 1GB (7-7-7-20) Patriot Viper DDR3-1333 2 x 2GB (7-7-7-20) |
| Video Card: | eVGA GeForce GTX 280 |
| Video Drivers: | NVIDIA ForceWare 190.62 (Win764) NVIDIA ForceWare 180.43 (Vista64) NVIDIA ForceWare 178.24 (Vista32) |
| Desktop Resolution: | 1920 x 1200 |
| OS: | Windows Vista Ultimate 32-bit (for SYSMark) Windows Vista Ultimate 64-bit Windows 7 64-bit |
Turbo mode is enabled for the P55 and X58 platforms.
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jasperjones - Tuesday, September 8, 2009 - link
Wonderful article as usual on AT. Read the articles on the website of your main competitor minutes before and didn't learn nearly as much about the LGA 1156 platform as I did here. Well done!I have one somewhat cheap comment. I always feel there's only one thing I do for which I really "need" my Core i7. And that's test-driving and debugging my well-threaded code (which makes use of OpenMP, MPI, threaded Intel MKL, etc.) before scp-ing it over to a cluster. Obviously, when testing code, I run using 8 threads. Still think that the Core i7 is probably more competitive in that area (performance/$ wise) than in the ones which this review focuses on (simply because I assume such code puts enough stress on the processors such that turbo-boosting is out of the question). On the other hand, I don't really care if gzip takes 2.5 or 3 seconds to compress a file (or if flac takes 8 or 9 seconds to encode my wav).
As I said, it's a cheap point. Just saying that I feel I primarily need "oomph" when running well-threaded stuff. Again, great article!
AeroWB - Tuesday, September 8, 2009 - link
Thanks for the interesting read, I do agree with some other people that some things are missing (clock for clock comparison) and some things are weird (core i7 with 1066DDR3). Some people are saying that everyone is overclocking their core i7, and while most readers of this article will probably be geeks that overclock I also read these articles as a systembuilder and I know that at least 95% of my customers don't overclock, so I really dig non-overclocked comparisons and results.There is also one thing I do not agree on, lets have another look at the page "The Best Gaming CPU?" and look to the DoWII results. What I see there is totally different from your conlusion though you do mention it in the text, the Bloomfield has lower minimum framerate then Lynnfield, but still your conclusion is Bloomfield is better then Lnynfield and Lynnfield is better then the Core2E8600. Ehm ???
Lets be clear the core i7 920 really sucks here as of its really low minimum fps you will have stutters. Great gaming is all about having a butter smooth FPS which dependent on the game type needs to be between 30 and 60 FPS. Basically the best game experience here will probably be with the E8600 as it has the highest minimum at 33 FPS which is great for RTS gaming. In order to say which CPU is best you should have an extra statistic like how much and how long the framerate dropped below 30FPS or something but as we do not have this data the minimum framerate is our next best thing. As weve seen before the Core i7 is good when using SLI/Crossfire but on par with the core2 when using a single GPU. Intel also told us themselfs that Core i7 was not made for gaming but for taking a bigger part in the server market. When increasing resolution/quality of gaming when using one GPU the Phenom 2 was often as fast and sometimes even faster then the Core i7. Unfortunately most CPU comparison with gaming are done at low to medium resolutions and quality so this effect couldn't be seen in most tests, but there were very few where this could be seen. So gaming with Core i7 920 only made sense when using SLI/Crossfire (as it scaled much better with these then Phenom2) or when paying the extra money (over Phenom2) because you used the system mostly for other task like video editing or so.
Now we can see this gaming problem of the Core i7 has been (at least partly) solved with Lynnfield, but still the Phenom2 965 has a higher minimum then the Core i5 750 so I would still prefer that one.
The other gaming test are not really relevant as all cpu's score a minimum of 60 FPS (ok one exception on 59) and so you won't notice any difference between all of the tested CPU's with those settings.
Still it is probable that the better gaming CPU in these test will also be better with higher settings, but as I have seen with the weird Core i7 / Phenom2 results I want to see tests with higher settings or test with more demanding games. And we want minimum and average results to determine which is best.
Sorry for the long post
iwodo - Tuesday, September 8, 2009 - link
I am waiting for SandyBridge or even Ivy Bridge for FMA.For now, a C2Q two years ago with money spent on graphics card will do fine.
The whole LGA socket and naming is a complete mess.
Dont get me wrong, it is a good Processors, but not the jump from Pentium 4 to C2D.
Money spend on SSD and Graphics is much better valued.
JonnyDough - Tuesday, September 8, 2009 - link
My dual core Opty 185 is still doing fine...Fallout 3 is still playable with my 8800GTS 640. The system has a slight OC and is chugging along at a minimum of 45FPS in the game on decent settings. Granted, it can't play every game - but I can only play one at a time anyway, and my life does not revolve around gaming. Hello...BEER PONG!Griswold - Tuesday, September 8, 2009 - link
I agree. I'll get excited when the 32nm dual cores with HT arrive. That would be a worthwhile "upgrade" (but a downgrade in number of cores, simply because I dont need 4 physical cores that much anymore) from my q6600 on a p35.Still, its a good product, just not worth an upgrade for everyone.
strikeback03 - Tuesday, September 8, 2009 - link
I was hoping there would be 32nm quads in this cycle, but it appears not. I'd definitely like something faster than my E6600/P965, but don't think it is worthwhile in time or money to just go to a C2Q.R3MF - Tuesday, September 8, 2009 - link
I spent much of the past year harping on AMD selling Nehalem-sized Phenom IIs for less than Intel sold Nehalems. With Lynnfield, Intel actually made Nehalem even >>>bigger<<< all while driving prices down.i think you mean smaller.
strikeback03 - Tuesday, September 8, 2009 - link
Nope, he meant bigger. Same process + more transistors = larger die, as is illustrated in the table.JonnyDough - Tuesday, September 8, 2009 - link
I think AMD realized years ago that they had awoken a sleeping giant, and it was a smart move to start thinking about competing graphically when they did. They saw how IBM had to change when Intel reared its ugly head. If you put all your eggs in one basket, you'll surely drop your next meal at some point. Diversifying into new markets was a smart move. Anyone who said that AMD didn't have good leadership didn't know what they were saying. Sure, money got really tight - but that's what has to happen to someone in a very competitive market at some point. Just take a look at GM. Giants crumble, little guys take over, and giants can muster a comeback...blyndy - Tuesday, September 8, 2009 - link
"I think AMD realised years ago that they had awoken a sleeping giant, and it was a smart move to start thinking about competing graphically when they did."That's an interesting thought.
I think there were to mains reasons why AMD acquired ATI.
1) in response to the news of Larrabee -- pre-emptive defensive move.
2)To diversify in preparation for Intels technological onslaught to finally kill its only CPU competitor.
So it may have been a smart move. On the other hand, knowing how patent riddled the CPU business is, maybe they could have ramped up R&D, but AMD is puny next to Intel.