Editing Front-side bus (section)

==Transfer rates==

The [[Bandwidth (computing)|bandwidth]] or maximum theoretical throughput of the front-side bus is determined by the product of the width of its data path, its [[Clock rate|clock frequency]] (cycles per second) and the number of data transfers it performs per clock cycle. For example, a 64-[[bit]] (8-[[byte]]) wide FSB operating at a frequency of 100&nbsp;MHz that performs 4 transfers per cycle has a bandwidth of 3200 [[megabytes per second]] (MB/s):

:8 bytes/transfer × 100 MHz × 4 transfers/cycle = 3200 MB/s

The number of transfers per [[Cycles per instruction|clock cycle]] depends on the technology used. For example, [[GTL+]] performs 1 transfer/cycle, [[Alpha_21264#External_interface|EV6]] 2 transfers/cycle, and [[AGTL+]] 4 transfers/cycle. Intel calls the technique of four transfers per cycle [[Quad Data Rate|Quad Pumping]].

Many manufacturers publish the frequency of the front-side bus in MHz, but marketing materials often list the theoretical effective signaling rate (which is commonly called [[Transfer (computing)|megatransfer]]s per second or MT/s). For example, if a motherboard (or processor) has its bus set at 200&nbsp;MHz and performs 4 transfers per clock cycle, the FSB is rated at 800 MT/s.

The specifications of several generations of popular processors are indicated below.

===Intel processors===

{|class="wikitable"
! CPU !! FSB Frequency (MHz) !! Transfers/Cycle !! Bus Width !! Transfer Rate (MB/sec)
|-
| [http://cpu-data.info/index.php?gr=135&lng=1 Pentium] || 50 - 66 || 1 || 64-bit || 400 - 528
|-
| [http://www.cpu-collection.de/?tn=0&l0=co&l1=Intel&l2=Pentium+OverDrive Pentium Overdrive] || 25 - 66 || 1 || 32 or 64-bit || 200 - 528
|-
| [http://ark.intel.com/products/family/2024 Pentium Pro] || 60 / 66 || 1 || 64-bit || 480 - 528
|-
| [http://cpu-data.info/index.php?gr=135&lng=1 Pentium MMX] || 60 / 66 || 1 || 64-bit || 480 - 528
|-
| [http://cpu-data.info/index.php?gr=137&lng=1 Pentium MMX Overdrive] || 50 / 60 / 66 || 1 || 64-bit || 400 - 528
|-
| [http://ark.intel.com/products/family/583 Pentium II] || 66 / 100 || 1 || 64-bit || 528 / 800
|-
| [http://ark.intel.com/products/family/2023 Pentium II Xeon] || 100 || 1 || 64-bit || 800
|-
| [http://www.cpu-world.com/CPUs/Pentium-II/Intel-Pentium%20II%20Overdrive%20333%20-%20PODP66X333%20%28UBPODP66X333%29.html Pentium II Overdrive] || 60 / 66 || 1 || 64-bit || 480 - 528
|-
| [http://ark.intel.com/products/family/590 Pentium III] || 100 / 133 || 1 || 64-bit || 800 / 1064
|-
| [http://ark.intel.com/products/family/590 Pentium III Xeon] || 100 / 133 || 1 || 64-bit || 800 / 1064
|-
| [http://cpu-data.info/index.php?gr=113&lng=1 Pentium III-M] || 100 / 133 || 1 || 64-bit || 800 / 1064
|-
| [http://ark.intel.com/products/family/581 Pentium 4] || 100 / 133 || 4 || 64-bit || 3200 - 4256
|-
| [http://cpu-data.info/index.php?gr=117&lng=1 Pentium 4-M] || 100 || 4 || 64-bit || 3200
|-
| [http://ark.intel.com/products/family/581 Pentium 4 HT] || 133 / 200 || 4 || 64-bit || 4256 / 6400
|-
| [http://ark.intel.com/products/family/581 Pentium 4 HT Extreme Edition] || 200 / 266 || 4 || 64-bit || 6400 / 8512
|-
| [http://ark.intel.com/products/family/7944 Pentium D] || 133 / 200 || 4 || 64-bit || 4256 - 6400
|-
| [http://cpu-data.info/index.php?gr=123&lng=1 Pentium Extreme Edition] || 200 / 266 || 4 || 64-bit || 6400 / 8512
|-
| [http://cpu-data.info/index.php?gr=124&lng=1 Pentium M] || 100 / 133 || 4 || 64-bit || 3200 / 4256
|-
| [http://cpu-data.info/index.php?gr=122&lng=1 Pentium Dual-Core] || 200 / 266 || 4 || 64-bit || 6400 / 8512
|-
| [http://cpu-data.info/index.php?gr=140&lng=1 Pentium Dual-Core Mobile] || 133 - 200 || 4 || 64-bit || 6400 - 8512
|-
| [http://ark.intel.com/products/family/288 Celeron] || 66 - 200 || 1-4 || 64-bit || 528 - 6400
|-
| [http://ark.intel.com/products/family/43401 Celeron Mobile] || 133 - 200 || 1-4 || 64-bit || 4256 - 6400
|-
| [http://ark.intel.com/products/family/5263 Celeron D] || 133 || 4 || 64-bit || 4256
|-
| [http://ark.intel.com/products/family/3799 Celeron M] || 66 - 200 || 1-4 || 64-bit || 528 - 6400
|-
| [http://cpu-data.info/index.php?gr=102&lng=1 Celeron Dual-Core] || 200 || 4 || 64-bit || 6400
|-
| [http://cpu-data.info/index.php?gr=142&lng=1 Celeron Dual-Core Mobile] || 133 - 200 || 4 || 64-bit || 4256 - 6400
|-
| [http://cpu-data.info/index.php?gr=150&lng=1 Itanium] || 133 || 2 || 64-bit || 2133
|-
| [http://www.cpu-world.com/CPUs/Itanium_2/index.html Itanium 2] || 200 - 333 || 2 || 128-bit || 6400 - 10666
|-
| [http://www.cpu-world.com/CPUs/Xeon/index.html Xeon] || 100 - 400 || 4 || 64-bit || 3200 - 12800
|-
| [http://ark.intel.com/products/family/18995 Core Solo] || 133 / 166 || 4 || 64-bit || 4256 / 5312
|-
| [http://ark.intel.com/products/family/22731 Core Duo] || 133 / 166 || 4 || 64-bit || 4256 / 5312
|-
| [http://ark.intel.com/products/family/32257 Core 2 Solo] || 133 - 200 || 4 || 64-bit || 4256 - 6400
|-
| [http://ark.intel.com/products/family/26547 Core 2 Duo] || 200 - 333 || 4 || 64-bit || 6400 - 10656
|-
| [http://ark.intel.com/products/family/26548 Core 2 Duo Mobile] || 133 - 266 || 4 || 64-bit || 4256 - 8512
|-
| [http://ark.intel.com/products/family/28398 Core 2 Quad] || 266 / 333 || 4 || 64-bit || 8512 / 10656
|-
| [http://ark.intel.com/products/family/37361 Core 2 Quad Mobile] || 266 || 4 || 64-bit || 8512
|-
| [http://ark.intel.com/products/family/34522 Core 2 Extreme] || 266 - 400 || 4 || 64-bit || 8512 - 12800
|-
| [http://ark.intel.com/products/family/34520 Core 2 Extreme Mobile] || 200 / 266 || 4 || 64-bit || 6400 / 8512
|-
| [http://ark.intel.com/products/family/29035 Atom] || 100 - 166 || 4 || 64-bit || 3200 - 5312
|}

===AMD processors===

{|class="wikitable"
! CPU !! FSB Frequency (MHz) !! Transfers/Cycle !! Bus Width !! Transfer Rate (MB/sec)
|-
| [http://cpu-data.info/index.php?gr=13&lng=1 K5] || 50&nbsp;-&nbsp;66 || 1 || 64-bit || 400&nbsp;-&nbsp;528
|-
| [http://cpu-data.info/index.php?gr=14&lng=1 K6] || 66 || 1 || 64-bit || 528
|-
| [http://cpu-data.info/index.php?gr=15&lng=1 K6-II] || 66&nbsp;-&nbsp;100 || 1 || 64-bit || 528&nbsp;-&nbsp;800
|-
| [http://cpu-data.info/index.php?gr=16&lng=1 K6-III] || 66 / 100 || 1 || 64-bit || 528&nbsp;-&nbsp;800
|-
| [http://cpu-data.info/index.php?gr=1&lng=1 Athlon] || 100 / 133 || 2 || 64-bit || 1600&nbsp;-&nbsp;2128
|-
| [http://cpu-data.info/index.php?gr=8&lng=1 Athlon XP] || 100 / 133 / 166 / 200 || 2 || 64-bit || 1600&nbsp;-&nbsp;3200
|-
| [http://cpu-data.info/index.php?gr=7&lng=1 Athlon MP] || 100 / 133 || 2 || 64-bit || 1600&nbsp;-&nbsp;2128
|-
| [http://www.cpu-world.com/CPUs/K7/TYPE-Mobile%20Athlon%204.html Mobile Athlon 4] || 100 || 2 || 64-bit || 1600
|-
| [http://cpu-data.info/index.php?gr=9&lng=1 Athlon XP-M] || 100 / 133 || 2 || 64-bit || 1600&nbsp;-&nbsp;2128
|-
| [http://cpu-data.info/index.php?gr=10&lng=1 Duron] || 100 / 133 || 2 || 64-bit || 1600&nbsp;-&nbsp;2128
|-
| [http://cpu-data.info/index.php?gr=24&lng=1 Sempron] || 166 / 200 || 2 || 64-bit || 2656&nbsp;-&nbsp;3200
|}