Build A PC
A custom PC configuration guide.
© 2000,2001,2002,2004 by Jef Poskanzer.
Sockets and Slots and Slotkets, Oh My
There are a bunch of different connectors used by CPUs.
AMD's socket for the Opteron and the Athlon 64-FX.
AMD's socket for the Athlon 64.
- mPGA603 / mPGA604
These are Intel's new sockets specifically for the Pentium-IV Xeon.
The socket equivalent of Slot-2.
The difference between the 603-pin version and the 604-pin version is
that Xeons with a 533MHz or 800MHz FSB have the extra pin, therefore they don't
fit into boards with the 603-pin socket.
The extra pin isn't connected to anything, it's just there to enforce
the bus speed difference.
The older 603-pin Xeons will fit into the 604-pin sockets and function
correctly, at their usual 400MHz bus speed.
Third-generation Pentium IV socket - started showing up in mid-2004.
Second-generation Pentium IV socket.
An update to the FC-PGA socket.
Backwards compatible - FC-PGA CPUs can be used in FC-PGA2 sockets.
Current info is that FC-PGA2 CPUs have a heat-spreader added, but it
is unclear what difference this makes for the socket.
In late 2000 Intel introduced the Pentium IV processor, and it uses a
new socket design with 423 pins.
This is not compatible with the 370-pin socket used by current Pentium IIIs,
nor (of course) with AMD's 453-pin Socket-A.
In mid-2000 AMD introduced the new Duron processor and the redesigned
Athlon, with on-chip full speed level-2 cache just like Intel's latest CPUs.
At that point they switched from a slot form back to a socket.
With Intel's high-density 0.18 micron process they can now fit
the level-2 cache on the main CPU chip, so the Slot-1 daughter board is
no longer necessary.
The form factor for these new chips is physically the same as the old
Socket-370, but the pinouts are somewhat different.
Still, you can get an adaptor to run an FC-PGA CPU in a Socket-370 motherboard.
With the Athlon Classic, AMD did the same thing as Intel, putting CPU and
level-2 cache on a little daughter board.
Their board was not compatible with Intel's though, perhaps for
Used by Intel's Xeon processors.
Similar to Slot-1, but with more memory lines.
You can get a very simple adaptor that lets you use a Slot-1 CPU
in a Slot-2 motherboard.
Used by later Celerons, and VIA's new M-III CPU.
With the later Pentium IIs and early Celerons, Intel started packaging the
main CPU chip plus some separate level-2 cache memory chips on a little
This is just because it wouldn't all fit onto a single chip.
Slot-1 is still used by the Pentium III line.
Not really a different connector, this refers to motherboards which
use Socket-7 but run it at 100MHz instead of 66MHz.
Still used by AMD's low-end CPUs, the K6-2 and K6-III.
Used by the Pentium Pro and early Pentium IIs.
The socket used by later Pentiums (early Pentiums used Socket-5).
In addition to the simple socket-to-socket and slot-to-slot adaptors
mentioned above, there are some socket-to-slot adaptors available,
which are generically called slotkets.
For instance, ABit sells one (actually the original SlotKET®) which
lets you use a Socket-370 CPU in a Slot-1 motherboard.
And if you need to know more, here's another
amazingly detailed page
all about CPU sockets.
Back to ACME Labs.