HP DC71XX, DX61XX 3.2.2 Processor Upgrading

Processor/Memory Subsystem

Figure 3-2 illustrates the internal architecture of the Intel Pentium 4 processor.

Pentium 4 Processor

Branch

16-K Execution

128-bit

Prediction

Trace Cache

Integer

8-K

L2

FPU

L1

1-MB

CPU

Adv..

Data

L2

Transfer

Rapid Exe. Eng.

Out-of-Order

Cache

Cache

FSB

ALUs

Core

I/F

Core speed

ALU Speed (Core speed x2)

FSB speed (max. data transfer rate)

Pentium Type

Core Speed

ALU Speed

FSB Speed

L2 Cache Size

P4 560

3.60 GHz

7.2 GHz

800 MHz

1 MB

P4 550

3.40 GHz

6.8 GHz

800 MHz

1 MB

P4 540

3.20 GHz

6.4 GHz

800 MHz

1 MB

P4 530

3.00 GHz

6.0 GHz

800 MHz

1 MB

P4 520

2.80 GHz

5.6 GHz

800 MHz

1 MB

Figure 3-2. Pentium 4 Processor Internal Architecture

The Intel Pentium 4 increases processing speed by using higher clock speeds with hyper-pipelined technology, therefore handling significantly more instructions at a time. The Pentium 4 features a branch prediction mechanism improved with the addition of an execution trace cache and a refined prediction algorithm. The execution trace cache can store 12 kilobytes of micro-ops (decoded instructions dealing with branching sequences) that are checked when re-occurring branches are processed. Code that is not executed (bypassed) is no longer stored in the L1 cache as was the case in the Pentium III.

The front side bus (FSB) of the Pentium 4 uses a 200-MHz clock but provides bi- and quad-pumped transfers through the use of 2x- and 4x-MHz strobes. The Pentium 4 processor is compatible with software written for x86 processors.

3.2.2 Processor Upgrading

All units use the LGA775 ZIF (Socket T) mounting socket. These systems require that the processor use an integrated heatsink/fan assembly. A replacement processor must use the same type heatsink/fan assembly as the original to ensure proper cooling.

The processor uses a PLGA775 package consisting of the processor die mounted “upside down” on a PC board. This arrangement allows the heat sink to come in direct contact with the processor die. The heat sink and attachment clip are specially designed provide maximum heat transfer from the processor component.

ÄCAUTION: Attachment of the heatsink to the processor is critical on these systems. Improper attachment of the heatsink will likely result in a thermal condition. Although the system is designed to detect thermal conditions and automatically shut down, such a condition could still result in damage to the processor component. Refer to the applicable Service Reference Guide for processor installation instructions.

ÄCAUTION: Installing a processor that is not supported by the system board may cause damage to the system board and/or the processor.

Technical Reference Guide 361834-002 3-3