Intel Socket 479 & 478 M (Mobile) CPU Upgrade (dothan)

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Intel's 478 socket was the standard pin layout for many years and was used in both desktop and mobile options for most of their Pentium 4 and Celeron range. Socket 478 was replaced by Intel's socket 775 as the standard pin layout for their desktop CPU range and for mobile options, socket 479 superseded socket 478. This is straightforward enough however there is a lot of confusion over what a socket 479 CPU actually is.

On Intel's CPU sSpec index, in their official documentation, Intel refer to most thier mobiles CPUs as socket (/package) type 'Micro-FCPGA', regardless of processor family (range). This adds massively to confusion over what is and isnt a socket 479 CPU and what CPUs are compatible with what laptops and motherboards.

Socket 478 processors are so called owing to the fact they have 478 pins. One would therefore assume a socket 479 CPU has 479 pins however this is not the case. They infact still have 478 pins but in a different layout.

The differences of how the 478 pins are laid out all occurs in the same, gold triangle marked, lower right hand corner of the CPUs below. The following three images show the three layouts:

The first image shows a standard socket 478 layout. This layout was used for most of Intel's Pentium 4 and Celeron desktop range. This layout is also used in the CPU range called 'Mobile Intel Pentium 4 Processor - M' which is often reffered to as the P4-M range. This range were based on Pentium 4 CPUs and are mostly green coloured, ceramic style CPUs (however there are some, e.g SL726 & SL725 that look like traditional socket 478 desktop CPUs (with silver coloured, metal top).

The second image shows what is normally referred to as a socket 479 CPU, this layout is used in the 'Intel Pentium M Processor' range. This range includes both Banias (early, 1mb L2 cache variations) and Dothan (standard, Centrino class 2mb L2 cache CPUs) core CPUs.

The third image above shows a further variation. Note the missing pins are still in a line like on the first, skt 478 photo however are aligned in a horizontal as opposed vertical orientation (depending of course on which way round the CPU is viewed from). This pin layout can be found in Intel's 'Mobile Intel Pentium 3 Processor' range. Ive included this to help users who come across but are unfamilar with this layout.

NOTE: There are now 'true' socket 479 CPUs available, Intel's Core Duo and Core Solo ceramic, green coloured CPU range DO have 479 pins, with just one pin missing from the corner where the gold triangle marker is shown above. I have not included an image on this to try and save further confusion. If you are unsure what CPU you have and/or want to upgrade your CPU, the best advise I can give is below:

Upgrading Your Laptop CPU

Obviously socket types are not interchangeable. If you are looking to upgrade your laptop CPU I would recommend first working out what CPU you currently have. This can be found using your laptop documentation, Googling your laptop make and model number, pehaps along with the word Pentium or by using a small utility programme, such as CPU-Z (link not included as not allowed by eBay Guide rules).

Once you know what 'family (an Intel term for product range) your CPU belongs to you can then find out which other CPUs are available from that family using Intel's sSpec guide that MAY be upgrade options for you. Once this information is obtained It is important to establish if your laptop has any upgrade limitations. The obvious one is if your laptop is limited in terms of Front Side Bus (FSB). E.g the Intel Pentium M range contains both 400Mhz and 533MHz FSB CPUs. Depsite they are from the same family, you may still be limited in CPU upgrade terms by your motherboard not being able to take 533MHz FSB CPUs. This information can often be found from the chipset manufacturer of your motherboard laptop or general internet and forum research, either asking others or checking existing forum posts for other people's opinions (always take with a pinch of salt) on upgrade possibilities.


This guide has been written and created by Peter Shaw. My Ebay User ID is SFFPCS & my listings can be accessed as nromal through eBay or directly through the domain name (which  redirects to eBay) www.  Thank you for reading this guide. If this guide was helpful please select YES on the bar below asking Was this guide helpful?. Thank you for your time

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