Intel Xeon L5420
Runs in an LGA 775 board only with the adapter sticker, the socket tabs removed and BIOS support for its core. How the mod works.
Intel Xeon L5420: 4-core, 2.5 GHz, Harpertown, LGA 771, 1333 MT/s FSB, 12 MB (2 x 6 MB) L2, 50 W TDP.
Clock for clock, the L5420 is the E5420 at a lower power rating: 2.5 GHz from a 1333 MT/s bus and a 7.5x multiplier, but a 50 W TDP. Two 45 nm dies give 12 MB of L2, and SSE4.1, VT-x and Enhanced SpeedStep are all there. VID runs 0.85 V to 1.35 V, and ARK sets Tcase at 57 °C. Intel's launch quarter is Q1 2008. C0 parts carry SLARP and report CPUID 10676; E0 parts carry SLBBR and report 1067A. For an always-on machine running a few virtual machines, four cores at modest heat make sense.
| Family | Xeon |
|---|---|
| Codename | Harpertown |
| Socket | LGA 771 |
| Cores / threads | 4 / 4 |
| Base clock | 2.5 GHz |
| Front-side bus | 1333 MT/s (333 MHz base clock) |
| Multiplier | 7.5x |
| L2 cache | 12 MB (2 x 6 MB) |
| TDP | 50 W |
| Process | 45 nm |
| Launch | Q1 2008 |
| Dual-socket capable | Yes |
| VT-x | Yes |
| SSE4.1 | Yes |
| Enhanced SpeedStep | Yes |
| Max case temperature | 57 °C |
| Voltage range (VID) | 0.85 V to 1.35 V |
Steppings and microcode IDs
| Stepping | CPUID | sSpec |
|---|---|---|
| C0 | 10676 | SLARP |
| E0 | 1067A | SLBBR |
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
Closest LGA 775 desktop chip: Core 2 Quad Q8300 (2.5 GHz, 1333 MT/s, 4 MB (2 x 2 MB)). A board that lists it is the best sign it can run the Xeon L5420.
Before the mod, confirm the board supports 45 nm Yorkfield quads in its current BIOS. Then fit the sticker, remove the two socket tabs, and add microcode for 10676 and 1067A with the LGA 771 platform ID. Back up the stock BIOS before flashing, so a bad write is a setback rather than a dead board.
Check a specific board with the LGA 771 to 775 compatibility checker.