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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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.