Socket AM3+

Socket AM3+
Release date	October 2011
Type	PGA-ZIF
Chip form factors	PGA
Contacts	942 (Socket); 938 (Socket AM3 CPU); 940 (Bulldozer Based CPU)
FSB protocol	HyperTransport 3.1
FSB frequency	200 MHz System clock; HyperTransport up to 3.2 GHz
Processors	Phenom II; Athlon II; FX; Opteron 3000 Series
Predecessor	AM3
Successor	AM4
Memory support	DDR3
	This article is part of the CPU socket series

Socket AM3+ is a modification of Socket AM3, which was released on February 9, 2009. AM3+ was released in mid-2011^[1] designed for CPUs which use the AMD Bulldozer microarchitecture and retains compatibility with processors made for AM3.^[2] The Vishera line of AMD CPUs also all use Socket AM3+. It is the last AMD socket for which Windows XP support officially exists.

Technical specifications

The AM3+ Socket specification contains a few noteworthy design changes over its AM3 predecessor. The 942 pin count for the AM3+ is an increase of one compared to the AM3 Socket layout.^[3] The AM3+ Socket has larger pin socket diameter of 0.51 mm compared to 0.45 mm with the AM3 Socket. There is a faster serial link of 3400 kHz from the CPU to the power controller, compared to 400 kHz. The AM3+ Socket offers improved power regulation and power quality specifications, including an increased maximum current support of 145 A versus 110 A. There is also a redesigned CPU cooler retention harness allowing for slightly better airflow for CPU cooling, while retaining cooler backward compatibility.^[4]

Compatibility

Processors accepted by the AM3+ socket

The 942-contact AM3+ socket accepts both the 940-pin AM3+ CPU and the 938-pin AM3 CPU. This backward compatibility is intentional.

Motherboards that can accept the AM3+ processor

AM3+ CPUs are not mechanically compatible with AM3 sockets as AM3+ CPUs have an additional pin that the AM3 socket can not accommodate. However, some manufacturers have found success in retrofitting AM3-technology motherboards for AM3+ processors by replacing the AM3 socket with AM3+ and providing a BIOS upgrade. This is called "AM3+ Ready".^[5] Potential incompatibilities with new AM3+ features include:

Sideband temperature sensor interface for reading the temperature from the CPU. Without knowing the temperature, CPU PWM fan headers may only run at full speed.
Certain power-saving features may not work, due to lack of support for rapid V_CORE switching.^[6]

While AM3+ CPUs can be inserted into AM2 or AM2+ sockets, AM3+ CPUs could not operate in motherboards designed for AM2+ or AM2 CPUs. These motherboards are designed for DDR2 memory but AM3+ CPUs only have a DDR3 memory controller.

Heatsink

The 4 holes for fastening the heatsink to the motherboard are placed in a rectangle with lateral lengths of 48 mm and 96 mm for AMD's sockets Socket AM2, Socket AM2+, Socket AM3, Socket AM3+ and Socket FM2. Cooling solutions should therefore be interchangeable.