Intel Core i5 And Core i7: Intel’s Mainstream Magnum Opus

P55: The Chipset’s Responsibilities Dwindle

Say farewell to Intel’s conventional three-component platform design. P55 (and very likely every desktop chipset moving forward) centers on a two-chip implementation consisting of the CPU and one piece of motherboard core logic. Surely, there’s a team of Nvidia engineers feeling pretty gosh-darned vindicated right now.  

With the memory and PCI Express controllers now part of Lynnfield (and graphics migrating that direction with Q1’s Clarkdale launch), there’s little else for a chipset to do except the functionality formerly handled by Intel’s ICH southbridge lineup. Thus, P55 gives you six 3 Gb/s SATA ports, a Gigabit Ethernet MAC, 14 USB 2.0 ports, HD Audio, and eight lanes of PCI Express 2.0 for peripheral connectivity. As an indication of how far southbridge technology has come in the last two years or so, P55 is wholly uninspiring.

There is some notable power savings here compared to X58, though. To begin, Lynnfield sports a 95W TDP. Bloomfield is 130W. The X58 Express IOH is a 22W part. That vanishes completely. P55 uses up to 4.7W. And ICH10R consumes up to 4.5W. Add it all up and you’re down more than 56W right off the bat.

Making The Connection

Intel’s most recent three-chip desktop platform, X58, employed a 25.6 GB/s QPI link between the Core i7 CPU and X58 IOH. It then used a 2 GB/s DMI connection between X58 and the ICH10 chipset component.

As we shift to P55 and its two-chip design, the northbridge gets absorbed into Core i5/Core i7, and we’re left with what amounts to a southbridge attached to the processor, even if Intel refers to this as a platform controller hub. As with the ICHes before it, P55 connects to its host (Lynnfield) through a DMI connection.

According to Intel, the DMI link between Lynnfield and P55 runs at 2 GB/s, similar to past-generation ICHes. Previously, that connection handled six lanes of PCI Express 1.1, SATA, USB 2.0, Gigabit Ethernet, and HD Audio. With the move to P55, most of those subsystems remain unchanged. However, the chipset now supports eight lanes of PCI Express 2.0.

Intel is nevertheless confident that its DMI link won't be saturated. The math doesn't lie, though. With the right combination of add-in storage and SSDs, it wouldn't be difficult to jam things up there.

Chris Angelini
Chris Angelini is an Editor Emeritus at Tom's Hardware US. He edits hardware reviews and covers high-profile CPU and GPU launches.
  • caamsa
    Dang! AMD better get their $4iT together. Now I need to decided between i7, i5 or phenom II when I do my next happens too fast. Looking forward to more reviews on the i5 and mb prices.
  • People need to be careful when comparing the i7-870 to a i7-920, alot of people pre-release were worried that the 1156 platform was going to dominate the 1366. However when you see the 870 out perform the 920 people need to remember that a 870 is double the price of a 920, and even when you factor in a motherboard a 920 setup comes out cheaper than a 870.

    Now the i5 750 on the other hand is great performance at a great price, and would certainly be the budget gamers new weapon of choice.

    I currently have an i7-920 setup which is my main rig and am very happy with it and not at all upset to the see the 870 outperform it (since the 870 would cost me twice as much). I also have had an i5 750 setup now for over a week (the 1156 processors and motherboards have been available here in Australia for nearly 2 weeks now) and it is an amazing processor for the price of it.

    So what am I trying to say? 1366 is still a good platform for the top end of the market. The i5 are fantastic new processors for their price, and the 1156 i7's are just confusing and I'm not really sure who they are going to appeal to? I could understand it if Intel launched the 1156 i7's in 6months time when alot of users are already using the 1156 platform and are looking to upgrade their CPU without a new mobo. But to anyone looking at getting a 870, just get an 920 and use the extra cash on the mobo and ram to go with it.
  • Nintendork
    A little confusing the charts.

    I would prefer a bench with HD4890. They scale better in CF.
  • aspireonelover
    I can tell, I'm gonna fall in love with the i5 processor
  • cabose369
    Intel needs to come up with a simplified naming system for their products. They are as bad as NVIDIA is right now in terms of naming their products.

    There is sooo much to learn and there is so much information here.... I feel confused!!
  • alikum
    Well, I just hope that the Core 2 Quads will drop in prices significantly so that I could grab the high-end one for my final LGA775 upgrade!
  • buzznut
    Well this is good news for consumers. I'm not certain why it took so long for Intel to make some mainstream proc like i5, but for intel fans it seems worth the wait.
    This will also compel AMD to bring some more value to the market. Nice article.
  • jawshoeaw
    damn, 150 watts at idle?? Is that just the cpu? I hope the gaming rigs built on these processors are not left on 24/7. My old AMD X2 3800 system including the monitor uses less than 150 watts at idle (50 of which is the 22" LCD).
  • unclewebb
    i7 Turbo is a good tool to monitor the multiplier of Core i5/i7 CPUs.

    It uses the method that Intel recommends in their November 2008 Turbo White Paper.
  • evolve60
    "Intel Core i7-920 Extreme (Bloomfield) 2.66 GHz, LGA 1366, 4.8 GT/s QPI, 8 MB L3, Power-savings enabled"

    Since when has the I7-920 become an extreme?