P55 Chipset Overview

We have just one chipset now as typical Northbridge functions are moved onto the Lynnfield processor. Just like its Bloomfield-based Core i7 big brother, Lynnfield based CPUs have integrated memory controllers. The DDR3 memory channels are dual channel unlike the triple channel setup on Bloomfield. Lynnfield currently supports 16GB of memory, solidly placing it in the midrange category. However, official memory speeds now reach 1333MHz instead of 1066MHz on Bloomfield. The biggest difference between the two processer families is that Lynnfield stuffs 16 lanes of PCI Express 2.0 connectivity into the processor, thus alleviating the need for a Northbridge.

Those 16 PCIe 2.0 lanes can be configured as a single x16 link or split between a pair of x8s for multi-GPU configurations with a set of PCIe switches. CrossFireX support is a given but SLI support depends upon the motherboard manufacturer providing the right amount of funds to Nvidia for certification. For those unwilling to just accept 16 PCIe 2.0 lanes, EVGA already has a P55 board featuring the nForce 200 bridge chip with full support for three-way SLI.

What was known as the Integrated Controller Hub (ICH) on previous chipsets (such as the ICH10R) is now referred to as the P55 Express Platform Controller Hub, or PCH. The chip is based on 65-nm process technology. As such, it is a lot smaller than the ICH10 series with a total die area of around 76.5 mm².

  AMD SB750 Intel ICH10R Intel P55
Additional PCI Express None 6 x1 PCIe 1.1 8 x 1 PCIe 2.0
USB 12 ports 12 ports 14 ports
SATA (300MB/s) 6 ports 6 ports 6 ports
PATA 2 channels None None
RAID* RAID 0/1/5/10 RAID 0/1/5/10 RAID 0/1/5/10
HD Audio Interface Yes Yes Yes
Ethernet Not Integrated Intel Gigabit LAN Intel Gigabit LAN
Northbridge Interface 4 lane PCIe 1.1 DMI 1Gb/s each direction, full duplex DMI 1Gb/s each direction, full duplex

The P55 Express PCH provides six 3 Gb/s SATA ports, 14 USB 2.0 ports, a Gigabit Ethernet MAC , HD Audio interface, and eight lanes of PCI Express 2.0 goodness all for about $40. That price tag buys you two additional USB ports and two additional PCIe lanes over the $3 ICH10R. One other change worth mentioning is that the Gigbit Ethernet MAC will use one of those PCIe lanes if enabled.

The PCI Express lanes are version 2.0 but Intel decided to limit their speed to PCIe 1.x specs at 2.5GT/s. Why? We believe with the DMI link continuing to operate at 1GB/s in each direction, a decent 6Gb/s SAS/SATA RAID card and a few upcoming 6Gb/s drives could easily saturate the link. The P55 Express PCH consumes a little over 4.5W during normal operation. Considering the specifications on AMD’s upcoming SB8xxx chipsets, it appears we have a PCH Gap brewing.

Index Gigabyte GA-P55M-UD2 Features


View All Comments

  • goinginstyle - Monday, October 05, 2009 - link

    I loved the review also and it showed a lot of work went into testing these boards. I just wonder when TA152H is going to ruin this thread but until then it nice to see constructive posts. I also wish the mobo guys would just drop the floppy and IDE ports when possible. It would free up board real estate and hopefully drop the cost a little more. Reply
  • papapapapapapapababy - Monday, October 05, 2009 - link

    not touching any of this at least it has Socket 775 mounting holes
    usb3 @ pci3 @sata6 and im there.
  • Docket - Monday, October 05, 2009 - link

    It is a shame that there are no Linux versions of the Gigabyte software reviewed here... oh well maybe some day in a distant future. Reply
  • mitt - Monday, October 05, 2009 - link

    Hallelujah! DPC latency benchmark in AnandTech reviews! Reply
  • mathew7 - Monday, October 05, 2009 - link

    When MB manufacturers are going to let go of PCI?
    I recently switched to Micro-ATX, and found I have a real problem of choosing a motherboard.
    I'm looking at buying a PCIe X-Fi, but would like to use a dual-slotted video card. But I would like to keep my options open for a second card (I'm htinking about physics, not SLI/CF, so dual-slot cooling is not required). While the Gigabyte does not pass my requirements, the Asrock also has a problem: usage of a dual-slot-cooled card inhibits the usage of the PCIex1 slot.

    I intend to switch to i5/P55 at the start of next year, so I'm watching closely.
  • Jaybus - Thursday, October 08, 2009 - link

    That will be a slow transition. There are still a lot of PCI adapters being sold out there, especially for some specialty markets like scientific instrumentation that take time to transition to new interfaces due to cost and low volume. Nevertheless, the demise of PCI is starting to happen. For most people it's not a big deal, because they only need 1 or 2 PCIe x16 slots for graphics cards and will never use the rest of the slots anyway. Reply
  • MadMan007 - Monday, October 05, 2009 - link

    Kind of funny but Intel is leading the pack in that specific area, their $200 (ugh) 'Extreme' DP55SB mATX P55 mobo has no PCI slots, also no PS/2, IDE or floppy. Maybe it's consistent since they ditched PS/2 and other legacy connectors on some boards a while back. No telling on the overclocking front but it is an 'extreme' board so it may have at elast some overclocking features. It has a couple of neat features actually, Bluetooth and Intel NIC. Reply
  • Jaybus - Thursday, October 08, 2009 - link

    And uATX is a good platform to remove PCI from. Why not drop it from uATX? They can always leave it on ATX boards for a while for those who absolutely need PCI slots. I think other manufacturers will follow that path very soon. Reply
  • MadMan007 - Monday, October 05, 2009 - link

    *bzzt* The only PCIe 2.0 lanes on a P55 platform are from the CPU. So look carefully at specs and double check with companies when they say their secondary slots, especially ones that aren't even 16x mechanical, are PCIe 2.0. The UD2's 4x electrical slot in particular is clearly not according to Gigabyte, the ASRock claims to be but I'm not sure how if all 16 CPU PCIe 2.0 lanes are used for the graphics slot. If they used a lane splitter to provide PCIe 2.0 lanes to the other slots it kind of defeats the purpose, and if so it would be good to check performance with those slots populated. Reply
  • MadMan007 - Monday, October 05, 2009 - link

    To follow up on this, the comment was based on the first few paragraphs. I looked over Intel's manual for their 'extreme' mATX board for my post about it and Intel actually states their mobo has PCIe 2.0 lanes to the additional PCIe slots. Not surprising for the 8x slot I guess but it is for the 1x slots and it seems unlikely Intel would misquote specs.

    On a related note there is one thing I've not seen yet from any review and that is how PCIe lanes get assigned, mainly to the primary 16x slot, when populating a secondary PCIe slot with a 1x or 4x card. Do the lane splitter chips assign 8x lanes to a secondary slot which has a 1x or 4x card or what? Not a huge deal but it's a little thing that would be nice to know.

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