Intel Pentium 4 HT 661 socket: LGA 775
The Intel Pentium 4 HT 661 uses the LGA 775 socket. It is an 86 W single-core Cedar Mill desktop part at 3.6 GHz with Hyper-Threading and 2 MB of L2 cache for performance towers.
- Socket
- LGA 775
- Launched
- 2006
- Cores and threads
- 1 and 2
- Base power
- 86 W
- Codename
- Cedar Mill
- Segment
- Desktop
- Family
- Intel Pentium 4 HT
- Clocks
- 3.6 GHz
Intel Pentium 4 HT 661 specifications
| Cores | 1 |
|---|---|
| Threads | 2 |
| Core architecture | Cedar Mill cores on 65 nm |
| Clocks | 3.6 GHz (no turbo) |
| Cache | 2 MB L2 |
| Processor base power (TDP) | 86 W |
| Manufacturing process | 65 nm |
| Memory support | DDR2 through the board chipset |
| Front side bus | 800 MT/s |
| PCI Express | PCIe from the board chipset |
| Integrated graphics | None (board video where fitted) |
| Multiplier | Locked |
| Package | LGA 775 |
Motherboard compatibility
Intel Pentium 4 HT 661 needs a motherboard with a LGA 775 socket. Chipset by chipset data for this codename is not recorded yet. See the LGA 775 chipset list and the board maker's CPU support list.
LGA 775 at a glance
| Type | LGA, 775 contacts |
|---|---|
| Package size | 37.5 × 37.5 mm |
| Introduced | 2004 |
| Memory | DDR, DDR2 or DDR3, depending on the motherboard chipset |
| Cooler mounting holes | 72 × 72 mm |
What the Pentium 4 HT 661 is
The Intel Pentium 4 HT 661 is a 3.6 GHz single-core desktop processor from 2006. It runs one NetBurst core at 3.6 GHz with Hyper-Threading, so 1 core gives 2 threads. Cache is 2 MB of L2 on a 65 nm process. Power is rated at 86 W on LGA 775, with a later D0 stepping at 65 W.
The 661 topped the Cedar Mill 6x1 line on an 800 MT/s bus with an 18x multiplier at about 401 dollars launch price. It exists because buyers wanted the fastest single-core NetBurst threads with 2 MB of cache on cooler 65 nm silicon.
Socket and motherboard compatibility
The 661 drops into LGA 775 boards with DDR2 memory and a BIOS that lists Cedar Mill Pentium 4 parts, such as 945 boards. It pairs with mainstream chipsets contemporary with Cedar Mill. The Socket vs chipset: what decides whether a CPU works guide covers pairing rules.
Memory, PCIe and cooling
Memory is DDR2 through the board chipset in two channels.
An 800 MT/s front side bus ties the CPU to the chipset. PCIe slots hang off the chipset.
Cooling is any 86 W rated LGA 775 heatsink on the 72 mm mount.
Upgrade paths
On LGA 775 the upgrade is the Intel Pentium D 915 at 2.8 GHz for dual cores in the 95 W class, or the Intel Pentium 4 HT 651 at 3.4 GHz for a lower cost single core. Beyond LGA 775 a move to a newer platform needs a new board and memory.
Frequently asked questions
What socket does the Pentium 4 HT 661 use?
LGA 775, on DDR2 boards with a Cedar Mill-aware BIOS.
How many cores does the Pentium 4 HT 661 have?
One core and 2 threads at 3.6 GHz with Hyper-Threading and 2 MB of L2 cache.
What memory works with the Pentium 4 HT 661?
DDR2 through the board chipset in two channels.
Sources and verification
Facts last checked against these sources on . Page last edited on .