Dell OptiPlex 7770 All In One OptiPlex 7770 All-in-One Service Manual - Page 9

Feature/Option, DDR 4 Advantages, DDR4 Details, Key notch differenc, Increased thickness, Curved edge

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Feature/Option Multi-Purpose Register DIMM Types DIMM Pins RAS DDR3 DDR4 DDR 4 Advantages Four Registers - 1 Defined, 3 RFU RDIMM, LRDIMM, UDIMM, SODIMM 240 (R, LR, U); 204 (SODIMM) ECC Four Registers - 3 Defined, 1 RFU RDIMM, LRDIMM, UDIMM, SODIMM 288 (R, LR, U); 260 (SODIMM) CRC, Parity, Addressability, GDM Provides Additional Specialty Readout More RAS features; improved data integrity DDR4 Details There are subtle differences between DDR3 and DDR4 memory modules, as listed below. Key notch difference The key notch on a DDR4 module is in a different location from the key notch on a DDR3 module. Both notches are on the insertion edge, but the notch location on the DDR4 is slightly different, to prevent the module from being installed into an incompatible board or platform. Figure 1. Notch difference Increased thickness DDR4 modules are slightly thicker than DDR3, to accommodate more signal layers. Figure 2. Thickness difference Curved edge DDR4 modules feature a curved edge to help with insertion and alleviate stress on the PCB during memory installation. Figure 3. Curved edge Technology and components 9

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Feature/Option
DDR3
DDR4
DDR 4 Advantages
Multi-Purpose Register
Four Registers – 1 Defined, 3
RFU
Four Registers – 3 Defined, 1
RFU
Provides Additional Specialty
Readout
DIMM Types
RDIMM, LRDIMM, UDIMM,
SODIMM
RDIMM, LRDIMM, UDIMM,
SODIMM
DIMM Pins
240 (R, LR, U); 204 (SODIMM)
288 (R, LR, U); 260 (SODIMM)
RAS
ECC
CRC, Parity, Addressability,
GDM
More RAS features; improved
data integrity
DDR4 Details
There are subtle differences between DDR3 and DDR4 memory modules, as listed below.
Key notch differenc
e
The key notch on a DDR4 module is in a different location from the key notch on a DDR3 module. Both notches are on the insertion edge,
but the notch location on the DDR4 is slightly different, to prevent the module from being installed into an incompatible board or platform.
Figure 1. Notch difference
Increased thickness
DDR4 modules are slightly thicker than DDR3, to accommodate more signal layers.
Figure 2. Thickness difference
Curved edge
DDR4 modules feature a curved edge to help with insertion and alleviate stress on the PCB during memory installation.
Figure 3. Curved edge
Technology and components
9