Intel Core 2 Quad Q9400
Drops into a supported LGA 775 board as it is; check the board's CPU list. How to check.
Intel Core 2 Quad Q9400: 4-core, 2.66 GHz, Yorkfield, LGA 775, 1333 MT/s FSB, 6 MB (2 x 3 MB) L2, 95 W TDP.
Middle of the Yorkfield-6M range: 2.66 GHz from a multiplier of 8 on the 1333 MT/s bus, with 6 MB of L2 split 2 x 3 MB across the two dies. It sits between the Q8400, same clock and less cache, and the Q9450, same clock and more. Launched in Q3 2008, it has one sSpec, SLB6B, on the R0 stepping with CPUID 1067A. The rest holds no surprises: 95 W TDP, Tcase 71.4 °C, VID 0.85 V to 1.3625 V. VT-x, SSE4.1 and Enhanced SpeedStep are all there, which makes it an easy all-rounder for an LGA 775 box that runs a virtual machine or two and software built for SSE4.1.
| Family | Core 2 Quad |
|---|---|
| Codename | Yorkfield |
| Socket | LGA 775 |
| Cores / threads | 4 / 4 |
| Base clock | 2.66 GHz |
| Front-side bus | 1333 MT/s (333 MHz base clock) |
| Multiplier | 8x |
| L2 cache | 6 MB (2 x 3 MB) |
| TDP | 95 W |
| Process | 45 nm |
| Launch | Q3 2008 |
| Dual-socket capable | No |
| VT-x | Yes |
| SSE4.1 | Yes |
| Enhanced SpeedStep | Yes |
| Max case temperature | 71.4 °C |
| Voltage range (VID) | 0.85 V to 1.3625 V |
Steppings and microcode IDs
| Stepping | CPUID | sSpec |
|---|---|---|
| R0 | 1067A | SLB6B |
A BIOS needs a microcode update matching the CPUID (and, for Xeons, the LGA 771 platform ID). See LGA 771 Xeon microcode and how to read your stepping.
Mod notes
No mod. Look the Q9400 up on the board maker's CPU list and match the R0 stepping and the first BIOS version given there; a board limited to a slower bus than 1333 MT/s is the wrong home for it.