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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maddoctor - Tuesday, September 8, 2009 - link
Yeah, I'm agree. I think AMD will be no more as a company next year. I hope it will be happen. I think it is better you throw your AMD rubbish products into the trash. Because, I don't see any valuable of it.Eeqmcsq - Tuesday, September 8, 2009 - link
Well, I hope that it does NOT happen, because we NEED competition to keep Intel honest. Secondly, I would not go as far as calling AMD stuff rubbish. They're good if they fit one's needs at the right price, but they are definitely getting pushed further down the totem pole.JonnyDough - Tuesday, September 8, 2009 - link
KEEP them honest? Where have you been?bupkus - Tuesday, September 8, 2009 - link
A Core i5 750 with HT would not only defeat the purpose of most of the i7s, but it would also widen the performance gap with AMD. Intel doesn't need to maintain a huge performance advantage, just one that's good enough.maddoctor - Tuesday, September 8, 2009 - link
I don't believe Intel will increasing its products because AMD does not have any competitive products.klatscho - Tuesday, September 8, 2009 - link
actually, they do - if you would care to have a look at price/performance, especially considering that amd has already quietly thinned out its portfolio to make room for price improvements in order to stay in the game.maddoctor - Tuesday, September 8, 2009 - link
Intel doesn't need to be honest. I hope Intel will lifts AMD licensee as AMD has been breached the Intel - AMD CLA. I believe Intel will always be innovating and makes more cheaper and performance wise products. AMD will be no more and you will not need to miss it, AMD had been doing its duty to made Intel more stronger and competitive.PrinceGaz - Tuesday, September 8, 2009 - link
You are a fool if you think AMD is no longer needed. The only reason these Lynnfield chips start at just $196 is because AMD is still here and were selling competitive chips at around that price point. No AMD means newer better chips are introduced at high price points and stay there for a long time, just look at Bloomfield's prices to see what happens when AMD offers no competition. The $284 i7 920 is for a slightly higher performing chip than any Phenom and is priced accordingly, but you have to pay $562 and then $999 for performance where there is truly no competition.No AMD would mean these Lynnfields starting at $284 if you're lucky (that's for something like the i5 750) with the HT enabled ones at the $562 price point, and the only chips you'd find for under $200 would be old Core 2 Duos and Quads. Thankfully AMD are here which is why new chips are introduced at competitive prices. No competition (from AMD) means no competitive prices, so if AMD go bust today, the next generation of Intel chips will start expensive, and stay expensive until they are replaced with the model after it, which won't be for a long time when nobody else can offer anything like their current product. I guess you don't remember the days of the original Pentium in the mid 90's.
ClagMaster - Tuesday, September 8, 2009 - link
I agree. We need AMD and it's foolish to assert otherwise.AMD has been very good to us over the last 10 years. If it was not for AMD, Intel would have a monopoly and we would have not have Lynnfield or Bloomfield today. Intel created Lynnfield because they wanted to be more competitive with AMD in the mainstream market. Bloomfield/X58 was simply too expensive for mainstream and AMD's Phenon II was a better value.
I am discouraged that people have so easily forgotten AMD's past leadership such as the efficient instruction schedulers, first on-chip memory controller,the first single-die dual and quad core chips to market, the first consumer 64-bit processors, the x86-64 architecture extension that Intel followed, and the K8 architecture that kicked Intel Netburst architecture's butt black and blue.
That's why Intel was motivated to drop Netburst and introduce the Core 2 Duo/P965 in 1996. Then adopt the aggressive tick-tock strategy ever since that has given us the 45nm Lynnfield today. Lynnfield has these AMD inspired innovations, and Intel has built upon these innovations with the on-die PCIe controller.
I have a lot of respect for AMD. Don't ever accuse AMD of not being innovative. AMD does not suffer from lack of technological innovation. They have demonstrated plenty of innovation. AMD suffers from lack of capital investment that allows acceleration of technological development and manufacturing infrastructure.
strikeback03 - Wednesday, September 9, 2009 - link
You can't really say Lynnfield is a response to PhenomII when it was on the Intel roadmap before they knew how PhenomII would perform or be priced. It is simply the next progression in their architecture. So you might be able to argue that Intel wouldn't have rolled out the Nehalem architecture as quickly without AMD, but you can't really say any one family is a response to another in that short a timescale.