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
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  • mfs - Friday, March 26, 2010 - link

    how do you get 4 phase on the GA-P55M-UD2? looks like 6 by the photos? bit-tech says 6 too.
  • andersbranderud - Friday, March 12, 2010 - link

    Does anyone have any experiences with overclocking an i7-860 on this motherboard with 1333 mhz or 1600 mhz ram.

    In that case give me some more details.


    Anders Branderud
  • zoggy - Thursday, February 18, 2010 - link

    Was looking at picking up GA-P55M-UD2 for a HTPC, going to pair it with Core i7 860 and a ATI HD 5000 series card. Wanted to know if there was any problems with this board to do the bit-streaming of HD audio or if the UD4 would be better suited?
  • Hrel - Friday, October 23, 2009 - link

    Pictures of the Motherboard BIOS, THANK YOU SO MUCH!
  • maomao0000 - Sunday, October 11, 2009 - link


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  • Googer - Sunday, October 11, 2009 - link

    I don't see how the inclusion of something can be seen as a negative. I am sure there are a few users who still depend on a floppy drive from time to time (retro dos gamers, some drivers, and archiving old files) and it's presence has little to negative impact on the actual usability, functionality, or performance of the motherboard.

    As for my self, I have tried several times to remove my drive, only to have someone or myself find an unexpected need for it a few months later. So I still keep it installed but the drive it's self remains disabled in the bios until I actually need it. Having it enabled has no noticeable impact on my P4 based system.
  • Serveo - Friday, October 9, 2009 - link

    Hi Gary,

    Nice review. I am planning to buy a p55 mATX board. There are some on the market but mostly they support only 16x & 4x GPU and thats a pity.

    Only the Gigabyte GA-P55M-UD4 and ASUS Maximus III Gene support sli/cross at 8x mode. I would like to your review about these boards soon. The price for the GA-P55M-UD4 is available around € 130.- incl. VAT and the Maximus III Gene around € 170.- incl VAT.

    Thats why I probably go for the Gigabyte due to the price an the board colors, but the board layout has some fails and according to the review at bit-tech.net the performance is not that good.

    Gary when can I aspect the review about these boards? Or which of these two board would you advice?
  • Awnold - Wednesday, October 7, 2009 - link

    Hi Gary,

    Great article! Looking at other user's experience w/ the Gigabyte board, I've seen a number of complaints w/ memory compatibility (e.g., Newegg's reviews). Would you mind posting the part #'s of the different memories you tested this board with?

    I did see your comment that the F4 BIOS improved memory compatibility, but to my knowledge they haven't updated their qualified memory list yet.

    Also, if other users on this forum have experience w/ this board, would you mind posting your memory config as well?

  • Awnold - Friday, October 9, 2009 - link

    I'm mostly curious about the G.Skill memory used. Does anyone have any success (or BSODs/failures) with the following modules:

  • haplo602 - Tuesday, October 6, 2009 - link

    stop with this P55 flood and finaly review a few 785G boards !!! please please PLEASE !!!

    I don't care about intel, I want to build an AMD PC and your site is severely lacking in that part ...

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