DDR3
RAM · 5 specs
Direct Answer
DDR3, standardized in 2007, kept DDR2's 240-pin DIMM count but switched from a rounded to a square notch in a different position, making the two physically incompatible despite the matching pin count. It dropped voltage to 1.5V (1.35V for the low-power DDR3L variant) and raised data rates up to DDR3-2133.
Source: JEDEC · Last reviewed Aug 28, 2026
Specs
| JEDEC Standard | 2007 |
| DIMM Pins | 240 (same count as DDR2; different notch shape and position -- not compatible) |
| SO-DIMM Pins | 204 |
| Nominal Operating Voltage | 1.5 (1.35V for DDR3L low-voltage variant) V |
| Data Rate Range | 800–2133 (DDR3-800 to DDR3-2133) MT/s |
Same Pin Count, Different Notch Shape
DDR3 reached JEDEC standardization in 2007. Like DDR2 before it, its 240-pin desktop DIMM count matches its predecessor's exactly -- but DDR3 changed the notch's actual shape, from rounded to square, in addition to shifting its position, making the two generations physically incompatible despite sharing a pin count for the second time in a row. The laptop SO-DIMM moved to a new 204-pin count.
DDR3 lowered standard operating voltage to 1.5V, with a widely-adopted 1.35V low-voltage variant (DDR3L) common in laptops for improved battery life, and a rarer 1.25V DDR3U variant. Data rates at launch ranged from DDR3-800 up to DDR3-2133 (roughly 400-1066 MHz I/O clock), a substantial jump over DDR2's ceiling.