• 2 PCI slots (full-height, full-length)
• 1 PCI Express x4 slot (x1 functionality)
• 1 PCI Express x16 slot for graphics

• 2 internal 3.5" bays
• 1 external 3.5" bay, 3 external 5.25" bays*

NOTE: Third external 5.25" bay is not full depth in side orientation.

2 USB 2.0, 1 IEEE 1394 (requires optional PCI card to function), 1 headphone out, and 1 microphone.

NOTE: Although HP Personal Workstations can be ordered with the HP Installer Kit for Linux and an IEEE 1394 card, HP cannot provide customer support for this configuration. Please refer to the Linux Hardware Support Matrix (http://www.hp.com/support/linux_hardware_matrix) for details, and to the Linux User Manual (http://www.hp.com/support/linux_user_manual) for tips on user-enablement of the IEEE 1394 Card.

xw4550T/PH2.6/F160/
U2.0/FX370z/p
RB419UA#ABA

xw4550T/PH2.6/F160/
U2.0/FX570z/p
RB420UA#ABA

xw4550T/PH2.8/F250/
U2.0/FX17z/p
RB421UA#ABA

Memory (Unbuffered DIMMs)

Configurations less than 1 GB are not supported on Microsoft Vista 64

PC2-5300E DDR2-667 ECC unbuffered DIMMs or PC2-5300 DDR2-667 non-ECC DIMMS
Only unbuffered DDR2 DIMMs (ECC unbuffered or non-ECC) are supported and must be x8 or x16 width. Memory upgrades are accomplished by adding DIMMs of the same or varied sizes.

ECC/Chipkill parameters
Chipkill on the HP xw4550 functions within these parameters:

• The workstation enables Chipkill functionality on paired ECC memory DIMMs only. When a single ECC DIMM is loaded, standard single bit correct and two bit detect ECC is supported.
• Chipkill can detect and correct up to four bit errors if the four bits are in the same symbol. That is, multiple bit errors in bits 0–3 or 4–7 of a byte can be detected and corrected. Multi-bit error that overlap or span symbol boundaries (bits 2–5 or 3–6, for example) cannot be corrected. For DIMMs that are based on x4 parts, this means that a single DRAM chip can fail and the system will continue to operate. For x8 and x16 parts, a complete DRAM chip cannot fail, but symbol errors will be corrected as described. Memory Scrubbing – xw4550 supports Sequential plus Source Correction Scrubbing
• Sequential Scrubbing
  In this mode, the scrubber sequentially proceeds through main memory, performing a read-write cycle or a read-modify-write cycle if a correctable error is found. The scrubber scrubs one cache line on each scrub interval that is programmable from 40 ns to 84 ms.
• Source Correction Scrubbing
  In this mode, the scrubber is directed to scrub any cache line that is the source of any corrected error during normal accesses. During normal operation when source correction scrubbing is disabled, single-bit errors are corrected on the fly and the corrected data is passed without updating the source memory location. When source scrubbing is enabled the scrubber also corrects the source memory location.
• Sequential Plus Source Correction Scrubbing
  When both sequential and source correction scrubbing are enabled, the scrubber sequentially proceeds through main memory. If a correctable error is detected during normal operation, the scrubber is redirected to the location of the error, and after it corrects that location in main memory it resumes sequential scrubbing at the previous location

Memory configuration suggestions
For best performance the total amount and type of memory loaded into Channel 1 and Channel 2 should be the same and should be loaded in pairs (two 512 MB DIMMs will have better performance than a single 1 GB DIMM). Match pairs by size and type. If these guidelines are not followed, your computer may not see all the RAM installed and may run the memory controller in a lower performance mode.

MAXIMUM MEMORY
Supports up to 4 GB DDR2-667 ECC Unbuffered or 2 GB DDR2-667 non-ECC SDRAM