168 Pin Registered SDRAM DIMM (Buffered) Pinout

Personal Computer Memory Module description, 168-pin Registered SDRAM DIMM Pin out.
The 168-pin DIMM have 84 pins per PWB side.
The Front Side board pinout contains left side pins 1-42, and right side pins 43-84.
The Back Side board pinout has left side pins 85-126, and right side pins 127-168.
Buffered 168-pin DIMM memory modules would be found in servers.

Front, Left Side Signals

Front-Side 168-pin Buffered Pin Out

Back, Left Side Signals

**168-Pin SDRAM DIMM PinOut**
Pin #	Pin name	Pin Description
85	VSS	Ground
86	DQ32	Data 32
87	DQ33	Data 33
88	DQ34	Data 34
89	DQ35	Data 35
90	VCC	+5 VDC or +3.3 VDC
91	DQ36	Data 36
92	DQ37	Data 37
93	DQ38	Data 38
94	DQ39	Data 39
95	DQ40	Data 40
96	VSS	Ground
97	DQ41	Data 41
98	DQ42	Data 42
99	DQ43	Data 43
100	DQ44	Data 44
101	DQ45	Data 45
102	VCC	+5 VDC or +3.3 VDC
103	DQ46	Data 46
104	DQ47	Data 47
105	CB4	Parity/Check Bit Input/Output 4
106	CB5	Parity/Check Bit Input/Output 5
107	VSS	Ground
108	NC	No Connection
109	NC	No Connection
110	VCC	+5 VDC or +3.3 VDC
111	/CAS	-
112	/CAS4	Column Address Strobe 4
113	/CAS5	Column Address Strobe 5
114	/S1	-
115	/RAS	-
116	VSS	Ground
117	A1	Address 1
118	A3	Address 3
119	A5	Address 5
120	A7	Address 7
121	A9	Address 9
122	BA0	-
123	A11	Address 11
124	VCC	+5 VDC or +3.3 VDC
125	Ck1	-
126	A12	Address 12

Back, Right Side Signals

**168-Pin SDRAM DIMM PinOut**
Pin #	Pin name	Pin Description
127	VSS	Ground
128	CKE0	-
129	/S3	Column Address Strobe 3
130	/CAS6	Column Address Strobe 6
131	/CAS7	Column Address Strobe 7
132	A13	Address 13
133	VCC	+5 VDC or +3.3 VDC
134	NC	No Connection
135	NC	No Connection
136	CB6	Parity/Check Bit Input/Output 6
137	CB7	Parity/Check Bit Input/Output 7
138	VSS	Ground
139	DQ48	Data 48
140	DQ49	Data 49
141	DQ50	Data 50
142	DQ51	Data 51
143	VCC	+5 VDC or +3.3 VDC
144	DQ52	Data 52
145	NC	No Connection
146	NC	No Connection
147	NC	No Connection
148	VSS	Ground
149	DQ53	Data 53
150	DQ54	Data 54
151	DQ55	Data 55
152	VSS	Ground
153	DQ56	Data 56
154	DQ57	Data 57
155	DQ58	Data 58
156	DQ59	Data 59
157	VCC	+5 VDC or +3.3 VDC
158	DQ60	Data 60
159	DQ61	Data 61
160	DQ62	Data 62
161	DQ63	Data 63
162	VSS	Ground
163	CK3
164	NC	No Connection
165	SA0	Serial Address 0
166	SA1	Serial Address 1
167	SA2	Serial Address 2
168	VCC	+5 VDC or +3.3 VDC

Data width is 64 bits per memory stick [the front side 84 pins are not connected together with the back side 84 pins]

The approximate board size. 5.375" x 1.375"

SIMM: Single Inline Memory Module
DRAM: Dynamic Random Access Memory
SO DIMM: Small Outline Dual Inline Memory Module
SDRAM:: Synchronous DRAM (Random Access Memory), Synchronous to Positive Clock Edge.
FPM:Fast Page Mode: (asynchronous) Obsolete, faster than normal DRAM, used in 386/486 computers.
EDO: Extended Data Out: (asynchronous) A superset of FPM, just faster than FPM.
All 168 pin DIMMs use either 66MHz SDRAM, PC100 SDRAM, PC133 SDRAM, EDO or FPM memory.
168 pin DIMMs have two alignment notches as shown.
The left most notch [key-way] determines the DRAM type.
If the notch is centered then the memory module is Buffered DRAM [EDO or Fast Page].
If the notch is off-set to the right then the memory module is either a un-buffered DRAM/SDRAM DIMM or a buffered SDRAM DIMM.
The center notch determines the voltage. If the notch is centered then the DIMM operates off 3.3 volts.

Back to the main Computer Memory Modules information page. For electronic device manufacturers see one of these pages:
Memory IC manufacturers [individual memory ICs]
Memory Module manufacturers [memory sticks]
Memory Module Acronyms [phrases used with memory sticks]
IC Memory Acronyms [phrases used with IC memory]
Additional electronic Equipment manufacturers may be found by selecting the OEM Equipment icon below.
Component manufacturers, including memory ICs, may be found by selecting the Components icon below.

Editor note; I'm not going to say that 168 pin DRAM buffered DIMMs are obsolete, but they are out-dated.
Of course the pin outs remain valid regardless of the age of the Memory Module.
In fact, at this point the pinouts, pin descriptions and signal names are set in stone.
Regardless of the continued usage of 168-pin DRAMs, they were Obsoleted by Double Data Rate memory.
More over, the current Memory Module format is DDR3, or the third generation of DDR, making this memory style very old.
So 168 pin DRAM buffered DIMM sticks should not be used in new designs.

Navigation: Engineering Home > OEM Equipment Vendors > Computer Gear > Memory Modules > Memory Module Pinout > 168 pin DIMM memory stick.


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