Intel Core 2 Extreme QX9775 socket: Socket 771
The Intel Core 2 Extreme QX9775 uses the Socket 771 socket. It is an unlocked 150 W quad-core Yorkfield Extreme part at 3.2 GHz with 12 MB of L2 cache for dual-socket Skulltrail.
- Socket
- Socket 771
- Launched
- March 2008
- Cores and threads
- 4 and 4
- Base power
- 150 W
- Codename
- Yorkfield
- Segment
- Desktop
- Family
- Intel Core 2 Extreme
- Clocks
- 3.2 GHz
Intel Core 2 Extreme QX9775 specifications
| Cores | 4 |
|---|---|
| Threads | 4 |
| Core architecture | Yorkfield cores on 45 nm |
| Clocks | 3.2 GHz (no turbo) |
| Cache | 12 MB L2 (2x6 MB) |
| Processor base power (TDP) | 150 W |
| Manufacturing process | 45 nm |
| Memory support | DDR2 FB-DIMMs at 800 MHz, up to 16 GB on D5400XS |
| Front side bus | 1600 MT/s |
| PCI Express | PCIe 1.1a x16 from the board chipset |
| Integrated graphics | None |
| Multiplier | Unlocked (Extreme Edition) |
| Package | LGA 771 |
| Core voltage | 1.35 V |
| Launch price | $1499 manufacturer tray price at launch |
Motherboard and chipset compatibility
Intel Core 2 Extreme QX9775 needs a motherboard with a Socket 771 socket. The table shows which chipset series accept it.
| Series | Chipsets | Support |
|---|---|---|
| Intel 5400 series | 5400 | Works out of the box |
Board makers publish a CPU support list for every model. Check it for your exact board before buying. Chipset details for Socket 771.
Socket 771 at a glance
| Type | LGA, 771 contacts |
|---|---|
| Package size | 37.5 × 37.5 mm |
| Introduced | May 2006 |
| Memory | DDR2 and DDR3 through the server board chipset |
| Cooler mounting holes | Board specific (server heatsink) |
What the Core 2 Extreme QX9775 is
The Intel Core 2 Extreme QX9775 is an unlocked 3.2 GHz enthusiast quad core from March 24, 2008. It runs four Yorkfield cores at 3.2 GHz with no turbo, so 4 cores give 4 threads. Cache is 6 MB of L2 per die, 12 MB total, on a 45 nm process with 820 million transistors. Power is rated at 150 W on Socket 771.
The QX9775 is the only Extreme dual-socket desktop chip, part SLANY at 1.35 V with a locked 8x base multiplier that tuners can raise freely, on a 1600 MT/s bus with VT-x virtualization. Unlike the QX9770 it runs only on the Intel D5400XS Skulltrail board, with ECC memory support and dual-socket operation for two chips in tandem. It exists because enthusiasts wanted an eight-core Skulltrail halo machine.
Socket and motherboard compatibility
The QX9775 fits the Intel D5400XS Skulltrail board with two LGA 771 sockets and FB-DIMM slots, the only listed platform. Standard LGA 771 Xeon boards do not take it. The Socket vs chipset: what decides whether a CPU works guide covers pairing rules.
Memory, PCIe and cooling
Memory is DDR2 FB-DIMMs at 800 MHz through the 5400 chipset, up to 16 GB on the D5400XS.
A 1600 MT/s front side bus ties each CPU to the chipset. Four PCIe 1.1a x16 slots hang off the board chipset.
Cooling must be top-notch server heatsinks rated for 150 W per socket, since Skulltrail holds eight cores at full speed.
Upgrade paths
On Socket 771 the QX9775 is the enthusiast ceiling, so the moves are Xeon 5400 Harpertown quads such as the Intel Xeon X5470 at 3.333 GHz for cheaper single chips, or the Intel Core 2 Extreme QX9770 at 3.2 GHz for single-socket LGA 775. Beyond Socket 771 a move to a newer Xeon platform needs new boards and memory.
Frequently asked questions
What socket does the Core 2 Extreme QX9775 use?
Socket 771, only on the Intel D5400XS Skulltrail board.
How many cores does the Core 2 Extreme QX9775 have?
Four cores and 4 threads at 3.2 GHz with 6 MB of L2 per die.
Is the Core 2 Extreme QX9775 unlocked?
Yes, Extreme Edition means an unlocked multiplier, and two chips run in tandem on Skulltrail.
Sources and verification
Facts last checked against these sources on . Page last edited on .