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Processor Speed Settings

This list is not comprehensive.


Notes:



486 CPU Speed Settings
 Bus Speeds (MHz)Jumpers
16202533405060BF
1.0x16202533405060--
2.0x3240506680100120on
12.5x40506383100125150--
3.0x486075100120150180off
4.0x6480100133160200240on
Notes:



586 CPU Speed Settings
 Bus Speeds (MHz)Jumpers
Socket 4   60 66             none
1.0x------60--66----------------------------
Socket 5 50 60 66             BF  
1.5x--75--90--100--------------------------off----
2.0x--100--120--133--------------------------on----
Socket 74050556062666875839095100105110112115120124133BF0BF1BF2
1.5x6075839094100103113125135143150158165168173180186200offoffoff
1.75x708896105109116120131146158166175184193196201210217233ononoff
2.0x80100110120125133137150166180190200210220224230240248266onoffoff
2.33x93117128140146156159175194210222233245256261268280289311offonon
2.5x100125138150156166171188208225238250263275280288300310333ononoff
2.66x107133147160166178182200222240253266280293299307320331356offoffon
3.0x120150165180188200205225250270285300315330336345360372400offonoff
3.33x133166183200208222228250278300317333350366373383400413444onoffoff
3.5x140175193210219233239263290315333350368385392403420434466offoffoff
4.0x160200220240250266273300333360380400420440448460480496533onoffon
4.5x180225248270281300308338375405428450473495504518540558600ononon
5.0x200250275300313333342375417450475500525550560575600620666offonon
5.5x220275303330344366376413458495523550578605616633660682733offoffon
6.0x240300330360375400410450500540570600630660672690720744800onoffoff
Notes:



The following chart lists all of the possible multipliers with each chip and what the motherboard setting is to get that multiplier. To use the chart, look at the top row and find what multiplier you want the chip to have. Then look at the leftside column for which chip. Where they meet on the chart shows what jumper setting(s) on the motherboard to use to achieve that multiplier with that specific chip.
Motherboard Multiplier Settings
AMD1.5x1.75x2.0x2.33x2.5x2.66x3.0x3.33x3.5x4.0x4.5x5.0x5.5x6.0xComments
AMD K5 SSA5
(Model 0)
1.5x--2.0x--The one multiplier pin (BF) only gives two options.
AMD K5 5k86
(Model 1)
1.5x
2.0x
2.5x
3.0x
--Model 1 added another multiplier pin (BF1), but only has a 1.5x multiplier on all of the possible settings.
AMD K5 5k86
(Model 2)
1.5x
2.0x
2.5x--Model 2 has both multiplier pins (BF0, BF1), and adds the 1.75x multiplier. I don't know what setting it to 3.0x will yield (probably 1.5x).
AMD K5 5k86
(Model 3)
1.5x
2.0x
2.5x3.0x--Model 3 is rare, but it does exist. Setting the mobo to 3.0x yields 2.0x on the chip (PR200). Has BF0 and BF1.
AMD1.5x1.75x2.0x2.33x2.5x2.66x3.0x3.33x3.5x4.0x4.5x5.0x5.5x6.0xComments
AMD K6
(Model 6)
--2.0x--2.5x--3.0x--1.5x
3.5x
--Has all three multiplier pins (BF0, BF1, BF2), but BF2 apparently is not yet active.
AMD K6
(Model 7)
--2.0x--2.5x--3.0x--1.5x
3.5x
4.0x4.5x5.0x5.5x--Has all three multiplier pins (BF0, BF1, BF2).
AMD K6-2
(Model 8)
--2.0x--2.5x--3.0x--1.5x
3.5x
4.0x4.5x5.0x5.5x--Three multiplier pins (BF0, BF1, BF2). 26050 CPU code.
AMD K6-2
(Model 8 CXT)
--2.5x--3.0x--1.5x
3.5x
4.0x4.5x5.0x5.5x2.0x
6.0x
Three multiplier pins (BF0, BF1, BF2). Adds 6.0x in place of 2.0x. 26351 CPU code.
AMD K6-III
(Model 9)
--2.5x--3.0x--1.5x
3.5x
4.0x4.5x5.0x5.5x2.0x
6.0x
Same as K6-2 CXT. Three multiplier pins.
AMD K6-2+
(Model D)
--2.5x--3.0x--1.5x
3.5x
4.0x4.5x5.0x5.5x2.0x
6.0x
Adds 2.0x in place of 2.5x setting. Three multiplier pins.
AMD K6-III+
(Model D)
--2.5x--3.0x--1.5x
3.5x
4.0x4.5x5.0x5.5x2.0x
6.0x
Same as K6-2+. Three multiplier pins.
Cyrix/IBM1.5x1.75x2.0x2.33x2.5x2.66x3.0x3.33x3.5x4.0x4.5x5.0x5.5x6.0xComments
Cyrix 6x86
(M1)
--2.0x--1.5x--3.0x--One documented multiplier pin (CLKMUL) and one undocumented (CLKMUL1). Only has whole number multipliers. For 1.0x mode, set to 2.5x.
Cyrix 6x86L
(M1L)
--2.0x--1.5x--3.0x--Same as 6x86. Two multiplier pins.
Cyrix 6x86MX
(M2)
1.5x--2.0x--2.5x--3.0x--Two multiplier pins (CLKMUL0, CLKMUL1).
Cyrix MII
(M2)
--2.0x--2.5x--3.0x--1.5x
3.5x
--Two multiplier pins (CLKMUL0, CLKMUL1).
Cyrix MII
(later M2: 6-0-1)
--2.0x--2.5x--3.0x--1.5x
3.5x
4.0x--Three multiplier pins (CLKMUL0, CLKMUL1, CLKMUL2).
IDT1.5x1.75x2.0x2.33x2.5x2.66x3.0x3.33x3.5x4.0x4.5x5.0x5.5x6.0xComments
IDT Winchip
(C6)
--2.0x
2.5x
--3.0x--1.5x
3.5x
4.0x
4.5x
--5.0x
5.5x
--Three multiplier pins (BF0, BF1, BF2), but it only has whole number multipliers.
IDT Winchip-2
(C6+)
--2.0x
2.5x
--3.0x--1.5x
3.5x
4.0x
4.5x
--5.0x
5.5x
--Same as Winchip.
IDT Winchip-2A
(C6+)
--5.0x2.5x5.5x3.0x2.0x1.5x
3.5x
4.0x4.5x--3 multiplier pins. Adds unusual 2.33x, 2.66x, and 3.33x multipliers.
IDT Winchip-2B
(C6+)
--2.0x
2.5x
--3.0x--1.5x
3.5x
4.0x
4.5x
--5.0x
5.5x
--Same as Winchip.
IDT Winchip-3
(C6-2L)
--5.0x2.5x5.5x3.0x2.0x1.5x
3.5x
4.0x4.5x--Same as Winchip-2A.
Intel1.5x1.75x2.0x2.33x2.5x2.66x3.0x3.33x3.5x4.0x4.5x5.0x5.5x6.0xComments
Intel Pentium
(P5 - 60/66)
--Runs at bus speed. No multiplier pins.
Intel Pentium OverDrive
(P5T - 120/133)
--Runs at 2x bus speed. No multiplier pins.
Intel1.5x1.75x2.0x2.33x2.5x2.66x3.0x3.33x3.5x4.0x4.5x5.0x5.5x6.0xComments
Intel Pentium Classic
(P54C)
1.5x--2.0x--2.5x--3.0x--Two multiplier pins (BF0, BF1).
Intel Pentium OverDrive
(P54CT)
--1.5x
2.0x
2.5x
3.0x
--Fixed 2.5x multiplier. Two useless multiplier pins (BF0, BF1).
Intel1.5x1.75x2.0x2.33x2.5x2.66x3.0x3.33x3.5x4.0x4.5x5.0x5.5x6.0xComments
Intel Pentium w/ MMX
(P55C: 5-4-4)
1.5x--2.0x--2.5x--3.0x--Earlier chips with the 5-4-4 stepping. Two multiplier pins (BF0, BF1).
Intel Pentium w/ MMX
(P55C: 5-4-3)
--2.0x--2.5x--3.0x--1.5x
3.5x
--Later chips with the 5-4-3 stepping. Two multiplier pins (BF0, BF1). Substitutes 3.5x multiplier for 1.5x.
Intel Pentium OverDrive w/ MMX
(P54CTB: 5-4-4)
--1.5x
2.0x
2.5x
3.0x
--125, 150, 166MHz CPUs. Fixed 2.5x multiplier. Two useless multiplier pins (BF0, BF1).
Intel Pentium OverDrive w/ MMX
(P54CTB: 5-4-3)
--1.5x
2.0x
2.5x
3.0x
--180 and 200MHz CPUs. Fixed 3.0x multiplier. Two useless multiplier pins (BF0, BF1).
Rise1.5x1.75x2.0x2.33x2.5x2.66x3.0x3.33x3.5x4.0x4.5x5.0x5.5x6.0xComments
Rise mP6
(step 3.0)
--2.0x--2.5x--Two multiplier pins (BF0, BF1).
Rise mP6
(step 4.1b)
--2.0x--2.5x--3.0x--1.5x
3.5x
--Two multiplier pins (BF0, BF1).
Notes:
1.) CLKMUL and BF are the same thing. CLKMUL is the Clock Multiplier on Cyrix/IBM chips. BF is the Bus Fraction (or Bus Frequency) on Intel chips. AMD, IDT, and Rise follow Intel's naming convention.

2.) In many cases, the motherboard manual will simply list all of the possible jumper settings with each chip to avoid having to decipher all this nonsense.

3.) Some versions of the Pentium Classic and Pentium w/ MMX chips have had their higher multipliers disabled. See Windwalker's site for more details.

4.) You can use ctcm16r to check the family, model, and stepping of the processor.

5.) If your Intel Pentium w/ MMX chip doesn't seem to be responding to the 3.0x and 3.5x multipliers (and you're sure it isn't a remarked chip), your motherboard may not be sending the correct signal to pin BF0 on the chip. Intel has a page describing the phenomenon. It occurs because Intel redefined the BF0 pin so that it has a pulldown resistor rather than the pullup that the Pentium Classic had. Some motherboard manufacturers may have assumed that the settings were the same, and decided to save a couple of pennies by not having the motherboard properly set the pin.

6.) The step 3.0 Rise mP6 chips have an errata that makes the 3.0x and 3.5x multipliers unusable. This is fixed in stepping 4.1b and later.



686 CPU Speed Settings
(Socket 8 / Slot 1 / Slot 2 / Socket 370)
 Bus Speeds (MHz)Jumpers
 50606668758390100102112124133150200BF0
LINT0
BF1
IGNNE#
BF2
A20M#
BF3
LINT1
1.5x7590100103113125135150154168186200225300offonoffoff
2.0x100120133137150166180200205224248266300400offoffoffoff
2.0x100120133137150166180200205224248266300400onononon
2.5x125150166171188208225250256280310333375500offononon
3.0x150180200206225250270300308336372400450600onoffonon
3.5x175210233240263292315350359392434466525700offoffonon
4.0x200240266274300333360400410448496533600800ononoffon
4.5x225270300308338375405450461504558600675900offonoffon
5.0x2503003333433754174505005135606206667501000onoffoffon
5.5x2753303663774134584955505646166827338251100offoffoffon
6.0x3003604004114505005406006156727448009001200onononoff
6.5x3253904334454885425856506667288068669751300offononoff
7.0x35042046648052558363070071878486893310501400onoffonoff
7.5x375450500514563625675750769840930100011251500offoffonoff
8.0x400480533548600666720800820896992106612001600ononoffoff
8.5x4255105665846387087658508679521054113312751700????
9.0x45054060061867575081090091810081116120013501800????
9.5x47557063365271379285595096910641178126614251900????
10.0x5006006676877508339001000102011201240133315002000????
10.5x5256307007217988759451100107111761302140015752100????
11.0x5506607337558259179901200112212321364146616502200????
Res.onoffoffoff
Notes:

Links

Upgrading With the K6 - c't article on upgrading the K6. Contains jumper settings.



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Last Updated: July/16/2001