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X58 vs. P55: Explaining Intel's Core i5/i7 Chipsets

written by: M.S. Smith•edited by: Simon Hill•updated: 5/19/2011

The introduction of the Core i5 also saw the introduction of the P55 chipset. Unlike previous chipsets, which were largely the same but introduced a few added features, the P55 and X58 have several major differences between them. Understanding the differences is a must before purchasing either.

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    A Tale of Two Chipsets

    With the release of Core i5 Intel has also introduced the new P55 chipset. Slotted below the X58 chipset, the P55 chipset is the successor to the P45 and is meant for more mainstream users who do not need certain high-end features. This has had a dramatic effect on price, as the least expensive P55 chipsets are priced around $100 dollars. That is about $60 dollars below the lowest-end X58 products.

    That said, buying a P55 or X58 motherboard is about more than price. There are significant differences between the two chipsets that buyers should be aware of. I will explore those differences and explain what they mean in layman's terms.

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    The Socket Issue

    New Core i5 processors fit into the LGA1156 socket on P55 motherboards Perhaps the most dramatic difference between the P55 and the X58 chipset is the CPU socket supported. X58 motherboards support the the LGA1366 socket, which is what was used by the first Core i7 processors and will also be used by Core i9 processors set for release in 2010. The P55 chipset, on the other hand, supports the LGA1156 socket. The LGA1156 socket can be used with Core i5 processors and some Core i7 processors, and will likely be compatible with future Core i3 processors.

    The socket difference creates an obvious disparity in the capabilities of the two chipsets because the two chipsets support different processors. This does not exactly mean that X58 supports higher performance processors, however, as the LGA1156 processors used with the P55 chipset have clockspeeds similar to the LGA1366 processors supported by X58. Instead, the main difference seems to be the number of cores. Intel's Core i9 processors are said to be six-core beasts with hyper-threading. These processors will be great for people who use programs that can make good use of multiple cores.

    Average users, however, will likely prefer the processors supported by LGA1156. Their performance in day-to-day tasks will be similar, but they will be much cheaper.

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    Dual-Channel Vs. Triple-Channel Memory

    The debut of the X58 chipset introduced triple-channel memory, designed for RAM modules to be used in pairs of three. Previous chipsets from both AMD and Intel had been using dual-channel memory, where RAM modules were to be used in pairs of two. In both cases the chipset does not have to be used in the recommended configuration. It is possible to install two RAM modules on an X58 motherboard and it will work but there is a performance hit associated.

    For average users, the difference between dual and triple channel memory configurations is hardly worth mentioning. The triple channel design used by the X58 chipset is capable of a higher peak performance, but no desktop system with either a P55 or X58 chipset is likely to become slowed because of memory performance. The triple channel memory configuration of the X58 is indicative of its targeting towards workstations and servers.

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    The PCI Express Fast Lane

    The third major difference between the X58 and P55 chipset exists in the way PCI Express functionality is handled. The X58 chipset's PCI Express controller is part of the chipset, which had traditionally been the case with all chipsets since PCI Express was introduced. The X58 chipset offers 40 PCI Express lanes which can be split up in numerous ways. This was impressive, as it allowed the X58 chipset to support two graphics cards at full x16 speed.

    The P55 chipset, however, actually incorporates the PCI Express controller into the processor. This has certain advantages, one of which is that it frees up room on the motherboard itself. Reviewers have commented that motherboards based off the P55 chipset have a good deal of room, and this is a direct result of Intel taking functionality which is traditionally part of the chipset and placing it on the processor.

    However, the PCI Express controller used with processors that run on the P55 chipset is much less robust than the controller on the X58 chipset, which means it cannot support two graphics cards at full x16 speed. The performance hit is not linear, but is enough to make a noticeable difference in graphics performance. Using multiple graphics cards with a P55 motherboard will result in lower performance than using multiple cards with an X58 motherboard. This said, there are ways of getting around the problem. Some motherboards come with an nForce 200 chip which allows SLI of multiple cards at full speed, and Lucid's Hydra chip will also bypass this limitation.

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    The Verdict

    Overall, P55 motherboards will be best for most users Overall, Intel's description of the P55 as a mainstream chipset is extremely accurate. The three differences listed here all have two things in common. First, each difference ends up technically in the favor of the X58. Second, each difference is only really an advantage for people who are using their computers for extremely specialized, high-end work loads. Most people don't need more than the 4 threads provided by the Core i5 processors, will not see the performance advantage available from triple-channel memory, and will not be using more than one video card.

    If you're a mainstream user, the P55 is exactly what you'll want. If you are looking to build a workstation, a server, or an extremely high-end gaming machine, then X58 is the chipset for you.