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Index

• Overview of Intel Processors
• Quality and other marks on Intel Pentium Processors
• Frequently asked questions about markings on Intel CPUs

486 Processors

Clock (MHz)	Proc	Volt	Ext clock	Pinout	Clock multipl.	Comments
25	(SX & DX)	5	25	486	1	(The DX Version has a FPU
33	(SX & DX)	5	33	486	1	Math Coprocessor built-in)
50	(DX)	5	50	486	1
DX/2 50	(SX & DX)	5	25	486	2	(The DX Version has a FPU
DX/2 66	(SX & DX)	5	33	486	2	Math Coprocessor built-in)
DX/4 75		5++ +++	25	486	3	(BOXDX40DPR75 repl 25MHz 486, or BOXDX40DP75 if overdrive socket present)
DX/4 100		5++ +++	33	486	3	(BOXDX40DPR100 repl 33MHz 486, or BOXDX40DP100 if overdrive socket present)
DX/4 75		3	25	486	3	(A80486DX475 OEM Version)
DX/4 100		3	33	486	3	(A80486DX4100 OEM Version)

Pentium^TM Processors

Clock (MHz)	Proc	Volt	Ext clock	Pinout	Clock multipl.	Comments
60		5	60	Pent 5V	1
63	OD	5 +++	25	486	2.5	(BOXPODP5V63 repl 25MHz 486)
66		5	66	Pent 5V	1
75		3	50	Pent 3V	1.5
83	OD	5 +++	33	486	2.5	(BOXPODP5V83 repl 33MHz 486)
90		3	60	Pent 3V	1.5
100		3	66+	Pent 3V	1.5
120		3	60	Pent 3V	2
120/133	OD	5 +++	60/66	Pent 5V	2	(BOXPODP5V133 repl 60 & 66MHz Pentium)
125	OD	3 +++	50	Pent 3V	2.5	(BOXPODP3V125 repl 75MHz Pentium)
133		3	66	Pent 3V	2
150		3	60	Pent 3V	2.5
150	OD	3 +++	60	Pent 3V	2.5	(BOXPODP3V150 repl 90MHz Pentium)
166		3	66	Pent 3V	2.5
166	OD	3 +++	66	Pent 3V	2.5	(BOXPODP3V166 repl 100MHz Pentium)
200		3	66	Pent 3V	3

Top and bottom view of a Pentium^TM processor.

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Pentium Pro^TM Processors

Clock (MHz)	Volt	Ext clock	Pinout	Clock multipl.
150	3	60	Pent Pro	2.5
166	3	66	Pent Pro	2.5
180	3	60	Pent Pro	3
200	3	66	Pent Pro	3

Top and bottom view of a Pentium Pro^TM processor.

Please note:
PCI Bus Clock is always half of the external CPU Clock speed (e.g. a P 166 will have a PCI Bus Clock of 33 MHz)
EISA & ISA Systems have at most a 8MHz Bus Clock (4.77MHz minimum).
XV is in reality 3.3V, however, it is usually simplified with a 3V specification.
+ Some motherboards connect a special pin to ground, forcing the processor to run on 50MHz externally.
++ The processor-core runs on 3.3V, however, the Voltageregulator on top of the chip converts the 5V supply to 3.3V
+++ This chip has a heat sink built in
All Overdrive (OD) Processors are direct chip replacements and require no modifiaction of the switch or jumper settings on the motherboard.
Generally speaking you can use a faster CPU w/ a slower clock speed (MHz), but you will not take full advantage of the processors speed capabilities.

Please click on the CPU in order to see the full screen picture.

Mark	Example	What it stands for
Processor type	A80502133	Where A80502 stands for Pentium Processor and 133 for the max. clock speed (i.e. 133 MHz). It could also be something like -75 which would be a 75 MHz CPU
Step No	SY022/SSS	Where SY022 stands for what lithography mask Intel used to make this particular processor (SSS see below).
Supply Voltage +	S	S stands for standard 3.135V to 3.6V. V stands for VRE with operating voltages narrowed it to 3.4V to 3.6V. This 'V' Version might not be compatible w/ the Powersupply in your PC
Timing Spec +	S	S stands for standard. M stands for Min Valid Delay Specification. This 'M' Version requires very strict timing from your system
MP Support +	S	S stands for standard where you can use the CPU in any Dual, Multi or single CPU configuration. U stands for Uniprocessor only, this version can not be used in a system with more than one CPU, and is typically suited for Desktop PC's
Embossed Lid +	iPP	iPP is the mark all 90MHz and faster CPU's carry most 75MHz Pentiums carry only the i75 symbol
ICOMP Index	1110	This is the standard Intel CPU speed index
Serial No	L6044482	The serial number consists of the actual number and the serialcode, together they form a unique number
Country of manufacturer +	MALAY	The CPU shown was manufactured in Intels Malaysia facility some people consider the CPU's made in the Philippines better, however, there is no real reason for this judgement. Intel does not mark all CPU's w/ the country of origin.

+ These marks are not on all CPU's manufactured by Intel.

Generally speaking a CPU made in the Philippines with a SSS mark after the step number is considered the best quality obtainable from Intel, however Intels practices make it virtually impossible to predict what grade of CPU's you receive, when the order is placed with Intel.
For most desktop PC's it is unimportant what grade of CPU is used, as the powersupply and Chip set tolerances are defined close enough in order to work with all CPU's and a second CPU can not be installed anyways.
A 90MHz CPU or faster with a i75 embossing are most likely fake, and should be reported to Intel, identifying the source if known.
Please Check CHIPLIST for a complete list of CPU types and detailed information on each.

Q What do the markings on the top and bottom of my processor mean?
A The family of the processor is always there on top, along with the product code and frequency. For example, A80502-90 means a 90 MHz version of the Pentium processor, model 2. Three-digit numbers following SX/SK/SU/SY/SZ are known as the s-spec numbers, and identify any specific characteristics that the part has, including the stepping, or version number. S-spec numbers are always printed on top of the package and are also on he bottom for newer versions of the Pentium processor. These SX numbers have nothing to do with previous products that we've had such as the Intel486 SX processor.
M C '92 '93 or M C '92 '95 are printed on the top and/or bottom. These dates give copyright information. They are not related to the date of manufacture of anyproduct.

Q I have heard that I can read the voltage specification directly from the package.
A Yes, for newer Pentium processors this is true. If a processor package has this information, it will be on the bottomside following the s-spec marking. The notation will be a slash mark followed by ABC, such as SK110 / ABC


Here is the decoding of ABC:

A)      S = standard voltage    (3.135 to 3.6V)
        V = VRE voltage         (3.4 to 3.6V)

B)      S = Part has standard timing specifications.
        M = Part has minimum valid MD timing specifications.

C)      S = Part was tested for a multi processing environment
        U = Not tested for dual-processing operation, but  only for uni-and multi-processing

Q I would like to know what voltage range my Pentium® processor requires. How do I determine this?
A If your processor does not have the voltage markings directly on the package (see above), use the s-spec number to determine this. The s-spec is a 3-digit number on the processor package which follows SX, SK, SU, SY, or SZ. Use the s-specs shown in the following table to find the voltage requirements for your part.
Basic 75-,90-,100-,133-,150- and 166 Mhz Pentium® Processor Identification Information
See the corresponding Note at the end of the table for items listing a number in the "Notes" column.


Type	Family	Model	Stepping	Mfg. Stepping	Core/bus MHz	S-Spec	Comments	Notes
0	5	2	1	B1	90/60	SX879	STD
0	5	2	1	B1	90/60	SX885	MD
0	5	2	1	B1	90/60	SX909	VR
2	5	2	1	B1	90/60	SX874	DP, STD
0	5	2	1	B1	100/66	SX886	MD
0	5	2	2	B1	100/66	SX910	VR, MD
0	5	2	2	B3	75/50	SX951	TCP Mobile
0	5	2	2	B3	90/60	SX923	STD
0	5	2	2	B3	90/60	SX922	VR
0	5	2	2	B3	90/60	SX921	MD
2	5	2	2	B3	90/60	SX942	DP, STD
2	5	2	2	B3	90/60	SX943	DP, VR
2	5	2	2	B3	90/60	SX944	DP, MD
0	5	2	2	B3	90/60	SZ951	STD	5
0	5	2	2	B3	100/66	SX960	VRE/ MD
0	5	2	4	B5	75/50	SX975	TCP Mobile
0 or 2	5	2	4	B5	75/50	SX961	STD
0 or 2	5	2	4	B5	75/50	SZ977	STD	5
0 or 2	5	2	4	B5	90/60	SX957	STD
0 or 2	5	2	4	B5	90/60	SX958	VR
0 or 2	5	2	4	B5	90/60	SX959	MD
0 or 2	5	2	4	B5	90/60	SZ978	STD	5
0 or 2	5	2	4	B5	100/66	SX962	VRE/MD
0	5	2	5	C2	75/50	SK079	TCP Mobile
0 or 2	5	2	5	C2	75/50	SX969	STD
0 or 2	5	2	5	C2	75/50	SX998	MD
0 or 2	5	2	5	C2	75/50	SZ994	STD	5
0 or 2	5	2	5	C2	75/50	SU070	STD	6
0 or 2	5	2	5	C2	90/60	SX968	STD
0 or 2	5	2	5	C2	90/60	SZ995	STD	5
0 or 2	5	2	5	C2	90/60	SU031	STD	6
0 or 2	5	2	5	C2	100/50 or 66	SX970	VRE/MD
0 or 2	5	2	5	C2	100/50 or 66	SX963	STD
0 or 2	5	2	5	C2	100/50 or 66	SZ996	STD	5
0 or 2	5	2	5	C2	100/50 or 66	SU032	STD	6
0	5	2	5	C2	120/60	SK086	VRE/MD
0	5	2	5	C2	120/60	SX994	VRE/MD
0	5	2	5	C2	120/60	SU033	VRE/MD	6
0	5	2	5	C2	133/66	SK098	MD
0	5	2	5	mA1	75/50	SK089	VRT, TCP	2,4
0	5	2	5	mA1	75/50	SK091	VRT, SPGA	2,4
0	5	2	5	mA1	90/60	SK090	VRT,TCP	2,4
0	5	2	5	mA1	90/60	SK092	VRT,SPGA	2,4
0 or 2	5	2	B	cB1	120/60	SK110	STD/no Kit	3,4
0 or 2	5	2	B	cB1	133/66	SK106	STD/no Kit	3,4
0 or 2	5	2	B	cB1	133/66	SK106J	STD/no Kit	3,4,7
0 or 2	5	2	B	cB1	133/66	SK107	STD	4
0 or 2	5	2	B	cB1	133/66	SU038	STD/no Kit	3,4,6
0	5	2	B	mcB1	100/66	SY029	VRT, TCP	2,4
0	5	2	B	mcB1	120/66	SK113	VRT, TCP	2,4
0	5	2	B	mcB1	120/66	SK118	VRT, TCP	2,4,7
0	5	2	B	mcB1	120/66	SX999	3.3V, SPGA	4
0 or 2	5	2	C	cC0	150/60	SY015	STD
0 or 2	5	2	C	cC0	150/60	SU071	STD	6
0 or 2	5	2	C	cC0	166/66	SY016	STD	3
0 or 2	5	2	C	cC0	166/66	SY017	VRE
0 or 2	5	2	C	cC0	166/66	SU072	VRE/no kit	3,6
0	5	2	C	cC0	166/66	SY037	VRE,PPGA	8,9
0	5	7	0	mA4	75/50	SK119	VRT, TCP	2,4
0	5	7	0	mA4	75/50	SK122	VRT, SPGA	2,4
0	5	7	0	mA4	90/60	SK120	VRT, TCP	2,4
0	5	7	0	mA4	90/60	SK123	VRT, SPGA	2,4
0	5	7	0	mA4	100/66	SK121	VRT, TCP	2,4
0	5	7	0	mA4	90/60	SK124	VRT, SPGA	2,4
0	5	2	C	mcC0	120/60	SY021	TCP,VRT	2
0	5	2	C	mcC0	120/60	SY027	SPGA 3.1V	2
0	5	2	C	mcC0	120/60	SY030	SPGA 3.3V	2
0	5	2	C	mcC0	133/66	SY019	TCP,VRT	2
0	5	2	C	mcC0	133/66	SY028	SPGA 3.1V	2
0	5	2	6	E0	75/500	SY009	TCP,Mobile
0 or 2	5	2	6	E0	75/50	SY005	STD
0 or 2	5	2	6	E0	90/60	SY006	STD
0 or 2	5	2	6	E0	100/66	SY007	STD
0 or 2	5	2	6	E0	120/60	SY033	STD

NOTES: For a definition of STD, VR, VRE, MD, VRE/MD, refer to Specification Changes 2 and 18 in this document. ES refers to Engineering Samples. DP indicates that this part can only be used as a dual processor. CPU Type of "2" or "0 or 2" indicates this part supports dual processing.

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The Type corresponds to bits [13:12] of the EDX register after RESET, bits [13:12] of the EAX register after the CPUID instruction is executed. This is shown as 2 different values based on the operation of the device as the primary processor or the dual processor upgrade.

The Family corresponds to bits [11:8] of the EDX register after RESET, bits [11:8] of the EAX register after the CPUID instruction is executed.
The Model corresponds to bits [7:4] of the EDX register after RESET, bits [7:4] of the EAX register after the CPUID instruction is executed.
The Stepping corresponds to bits [3:0] of the EDX register after RESET, bits [3:0] of the EAX register after the CPUID instruction is executed.


1. TCASE = 60C.
2. VRT Intel's Voltage Reduction Technology: The VCC for I/O is 3.3V, but the core VCC, accounting for about 90% of power usage, is reduced to 2.9V, to reduce power consumption and heating.
3. No Kit means that part meets the specifications but is not tested to support 82498/82493 and 82497/82492 cache timings
4. STEPPING The cB1 stepping is logically equivalent to the C2-step, but on a different manufacturing process. The mcB1 step is logically equivalent to the cB1 step (except it does not support DP, APIC or FRC). The mcB1, mA1, mA4 and mcC0-steps also use Intel's VRT (Voltage Reduction Technology, see note 2 above) and are available in the TCP and SPGA package, primarily to support mobile applications. All mobile steppings are distinguished by an additional "m" prefix, for "mobile".
5. This is a boxed Pentium processor without the attached fan heatsink.
6. This is a boxed Pentium processor with an attached fan heatsink.
7. These parts do not support boundary scan. S106J was previously marked (and is the same as) SK106J.
8. DP, FRC and APIC features are not supported on these parts.
9. These parts are packaged in the Plastic Pin Grid Array (PPGA) package. For additional specifications of this package, see specification clarifications 27 and 28.
Q So what is a stepping?
A The first version of a new microprocessor product is the A-0 step; later as we make improvements to the product for functional (bug) fixes or manufacturing improvements we will increase the stepping number. Generally speaking, minor changes result in an ncreased number, (i.e. A-3 to A-4) while more complex changes result in the letter being changed.(i.e. A-3 to B-0)

If you would like to know which stepping of the Pentium® processor you have, the CPUID utility program will report this information. Each manufacturing stepping has a unique stepping ID which can be read by the CPUID program.