AGP (Accelerated Graphics port) Pin Details With Voltage

ALL ABOUT AGP SLOT,PIN DETAILS AND VOLTAGES FOR MOTHERBOARD REPAIR

The Accelerated Graphics Port (also called Advanced Graphics Port) is a high-speed point-to-point channel for attaching a single device (generally a graphics card) to a computers motherboard, primarily to assist in the acceleration of 3D computer graphics. Many classify AGP as a type of computer bus, but this is something of a misnomer since buses generally allow multiple devices to be connected, while AGP does not. AGP originated from Intel, and it was first built into a chipset for the Pentium II microprocessor
. AGP cards generally slightly exceed PCI cards in length and can be recognized by a typical hook at the inner end of the connector, which does not exist on PCI cards. Nowdays AGP is almost replaced by PCI-Express.
AGP versions:

• AGP 1.0: 3.3 volts signaling with speed multipliers 1x (267MB/s), 2x (533MB/s)
• AGP 2.0: 1.5 volts signaling with speed multipliers 1x (267MB/s), 2x (533MB/s), 4x (1067MB/s)
• AGP 3.0: 0.8 volts signaling with speed multipliers 4x (1067MB/s), 8x (2133MB/s)

In addition, in the world of workstations different AGP Pro cards exist with extra connectors which allow card to draw more power. In order to make life easier, the AGP standard defines some backward compatibilty. The AGP 1.0 specification requires that all implementations support the 1x speed multiplier at 3.3 volts. By default, when the AGP 1.0 machine powers up it selects the fastest speed multiplier supported by both the video card and the motherboard. If they both support 2x then they will run at 2x. Otherwise they run at 1x which is always implemented by all AGP 1.0 video cards and motherboards. The AGP 2.0 specification has a similar requirement. 2x and 1x support at 1.5 volts are required and 4x support is optional. The AGP 3.0 specification requires support for 8x. The 3.0 specification isn't as clear as the 1.0 and 2.0 specifications on the subject of requiring the lower multiplier but all AGP 3.0 almost all implementations support both 8x and 4x. As a result, you can completely ignore speed multipliers when you're checking for compatibility between an AGP video card and an AGP motherboard. If the video card and motherboard both support the same signaling voltage then there is always at least one common speed multiplier supported by both at that voltage. You only need to make sure that the video card and motherboard have at least one signaling voltage in common.
AGP cards and slots

Graphics Card Types	Connector Type*	Description
AGP 3.3V Card	3.3V slot	Supports only 3.3V signaling. Available speeds 1x, 2x.
AGP 1.5V Card	1.5V slot	Supports only 1.5V signaling. Available speeds 1x, 2x, 4x.
Universal AGP Card	Double slotted	Supports 3.3V and 1.5V signaling. Available speeds 1x, 2x at 3.3V and 1x, 2x, 4x at 1.5V.
AGP 3.0 Card	1.5V slot	Supports only 0.8V signaling. Available speeds 4x, 8x.
Universal 1.5V AGP 3.0 Card	1.5V slot	Supports 1.5V and 0.8V signaling. Available speeds 1x, 2x, 4x at 1.5V and 4x, 8x at 0.8V.
Universal AGP 3.0 Card	Double slotted	Supports AGP 3.3v, 1.5V, and 0.8V signaling. Available speeds 1x, 2x at 3.3V and 1x, 2x, 4x at 1.5V and 4x, 8x at 0.8V.

*Different slots connectors have different position of key The AGP connectors on the motherboard are keyed to prevent insertion of AGP cards which would be damaged if plugged in. An AGP 3.3V motherboard connector can only accept AGP cards which have the 3.3V slot. If you try to insert a card without a 3.3V slot into an AGP 3.3V motherboard connector, the card will bump into the connector key and cannot be inserted. Likewise an AGP 1.5V motherboard connector can only accept AGP cards with the 1.5V slot. An AGP universal motherboard connector has no keys and therefore can accept any kind of AGP card. An AGP card with both voltage slots can be plugged into any kind of AGP motherboard connector. If you can plug an AGP card into an AGP motherboard connector, then neither the card nor the motherboard will be damaged (assuming they obey the AGP specifications).

AGP pinout

	3.3 Volt Boards		Universal Boards		1.5 Volt Boards
Pin #	Side A	Side B	Side A	Side B	Side A	Side B
1	+12V	OVRCNT#	+12V	OVRCNT#	+12V	OVRCNT#
2	TYPEDET#	+5.0V	TYPEDET#	+5.0V	TYPEDET#	+5.0V
3	Reserved	5.0V	Reserved	5.0V	Reserved	5.0V
4	USB-	USB+	USB-	USB+	USB-	USB+
5	Ground	Ground	Ground	Ground	Ground	Ground
6	INTA#	INTB#	INTA#	INTB#	INTA#	INTB#
7	RST#	CLK	RST#	CLK	RST#	CLK
8	GNT#	REQ#	GNT#	REQ#	GNT#	REQ#
9	VCC 3.3	VCC 3.3	VCC 3.3	VCC 3.3	VCC 3.3	VCC 3.3
10	ST1	ST0	ST1	ST0	ST1	ST0
11	Reserved	ST2	Reserved	ST2	Reserved	ST2
12	PIPE#	RBF#	PIPE#	RBF#	PIPE#	RBF#
13	Ground	Ground	Ground	Ground	Ground	Ground
14	Reserved	Reserved	WBF#	Reserved	WBF#	Reserved
15	SBA1	SBA0	SBA1	SBA0	SBA1	SBA0
16	VCC 3.3	VCC 3.3	VCC 3.3	VCC 3.3	VCC 3.3	VCC 3.3
17	SBA3	SBA2	SBA3	SBA2	SBA3	SBA2
18	Reserved	SB_STB	SB_STB#	SB_STB	SB_STB#	SB_STB
19	Ground	Ground	Ground	Ground	Ground	Ground
20	SBA5	SBA4	SBA5	SBA4	SBA5	SBA4
21	SBA7	SBA6	SBA7	SBA6	SBA7	SBA6
22	Key	Key	Reserved	Reserved	Reserved	Reserved
23	Key	Key	GROUND	GROUND	GROUND	GROUND
24	Key	Key	Reserved	3.3Vaux	Reserved	3.3Vaux
25	Key	Key	Vcc 3.3	Vcc 3.3	Vcc 3.3	Vcc 3.3
26	AD30	AD31	AD30	AD31	AD30	AD31
27	AD28	AD29	AD28	AD29	AD28	AD29
28	VCC 3.3	VCC 3.3	VCC 3.3	VCC 3.3	VCC 3.3	VCC 3.3
29	AD26	AD27	AD26	AD27	AD26	AD27
30	AD24	AD25	AD24	AD25	AD24	AD25
31	Ground	Ground	Ground	Ground	Ground	Ground
32	Reserved	AD STB1	AD STB1#	AD STB1	AD STB1#	AD STB1
33	C/BE3#	AD23	C/BE3#	AD23	C/BE3#	AD23
34	Vddq 3.3	Vddq 3.3	Vddq	Vddq	Vddq 1.5	Vddq 1.5
35	AD22	AD21	AD22	AD21	AD22	AD21
36	AD20	AD19	AD20	AD19	AD20	AD19
37	Ground	Ground	Ground	Ground	Ground	Ground
38	AD18	AD17	AD18	AD17	AD18	AD17
39	AD16	C/BE2#	AD16	C/BE2#	AD16	C/BE2#
40	Vddq 3.3	Vddq 3.3	Vddq	Vddq	Vddq 1.5	Vddq 1.5
41	FRAME#	IRDY#	FRAME#	IRDY#	FRAME#	IRDY#
42	Reserved	3.3Vaux	Reserved	3.3Vaux	KEY	KEY
43	Ground	Ground	Ground	Ground	KEY	KEY
44	Reserved	Reserved	Reserved	Reserved	KEY	KEY
45	VCC 3.3	VCC 3.3	VCC 3.3	VCC 3.3	KEY	KEY
46	TRDY#	DEVSEL#	TRDY#	DEVSEL#	TRDY#	DEVSEL#
47	STOP#	Vddq 3.3	STOP#	Vddq	STOP#	Vddq 1.5
48	PME#	PERR#	PME#	PERR#	PME#	PERR#
49	Ground	Ground	Ground	Ground	Ground	Ground
50	PAR	SERR#	PAR	SERR#	PAR	SERR#
51	AD15	C/BE1#	AD15	C/BE1#	AD15	C/BE1#
52	Vddq 3.3	Vddq 3.3	Vddq	Vddq	Vddq 1.5	Vddq 1.5
53	AD13	AD14	AD13	AD14	AD13	AD14
54	AD11	AD12	AD11	AD12	AD11	AD12
55	Ground	Ground	Ground	Ground	Ground	Ground
56	AD9	AD10	AD9	AD10	AD9	AD10
57	C/BE0#	AD8	C/BE0#	AD8	C/BE0#	AD8
58	Vddq 3.3	Vddq 3.3	Vddq	Vddq	Vddq 1.5	Vddq 1.5
59	Reserved	AD STB0	Reserved	AD STB0#	Reserved	AD STB0#
60	AD6	AD7	AD6	AD7	AD6	AD7
61	Ground	Ground	Ground	Ground	Ground	Ground
A62	AD4	AD5	AD4	AD5	AD4	AD5
63	AD2	AD3	AD2	AD3	AD2	AD3
Vddq 3.3	Vddq	Vddq	Vddq 1.5	Vddq 1.5
65	AD0	AD1	AD0	AD1	AD0	AD1
66	Reserved	Reserved	Vrefcg	Vrefcg	Vrefcg	Vrefcg

The AGP bus is 32 bits wide, just the same as PCI is, but instead of running at half the system (memory) bus speed the way PCI does, it runs at full bus speed. This means that on a standard Pentium II motherboard AGP runs at 66 MHz instead of the PCI buss 33 MHz. This of course immediately doubles the bandwidth of the port; instead of the limit of 127.2 MB/s as with PCI, AGP in its lowest speed mode has a bandwidth of 254.3 MB/s. The AGP specification is in fact based on the PCI 2.1 specification, which includes a high-bandwidth 66 MHz speed.
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