USB2 reconnu USB1 [ASUS P5B]

Bonjour,
Les ports USB 2.0 de mon Ordi, sont reconnu en USB 1. Ma carte mère est une ASUS P5B
J'ai envie de dire "comment se fesse ? et surtout comment y remédier ?"
Si ça peut servir, voici le rapport CPU-Z :
CPU-Z 1.39 report file
Processor(s)
Number of processors 1
Number of cores 2 per processor
Number of threads 2 (max 2) per processor
Name Intel Core 2 Duo E6300
Code Name Conroe
Specification Intel(R) Core(TM)2 CPU 6320 @ 1.86GHz
Package Socket 775 LGA
Family/Model/Stepping 6.F.6
Extended Family/Model 6.F
Core Stepping B2
Technology 65 nm
Core Speed 1601.2 MHz
Multiplier x Bus speed 6.0 x 266.9 MHz
Rated Bus speed 1067.5 MHz
Stock frequency 1866 MHz
Instruction sets MMX, SSE, SSE2, SSE3, SSSE3, EM64T
L1 Data cache 2 x 32 KBytes, 8-way set associative, 64-byte line size
L1 Instruction cache 2 x 32 KBytes, 8-way set associative, 64-byte line size
L2 cache 4096 KBytes, 16-way set associative, 64-byte line size
Chipset & Memory
Northbridge Intel P965/G965 rev. C2
Southbridge Intel 82801HB/HR (ICH8/R) rev. 02
Graphic Interface PCI-Express
PCI-E Link Width x16
PCI-E Max Link Width x16
Memory Type DDR2
Memory Size 2048 MBytes
Memory Frequency 266.9 MHz (1:1)
CAS# Latency (tCL) 4.0 clocks
RAS# to CAS# (tRDC) 4 clocks
RAS# Precharge (tRP) 4 clocks
Cycle Time (tRAS) 12 clocks
Command Rate 2T
System
System Manufacturer System manufacturer
System Name System Product Name
System S/N System Serial Number
Mainboard Vendor ASUSTeK Computer INC.
Mainboard Model P5B
BIOS Vendor American Megatrends Inc.
BIOS Version 1102
BIOS Date 01/30/2007
Memory SPD
Module 1 DDR2, PC2-4300 (266 MHz), 1024 MBytes, Kingston
Module 2 DDR2, PC2-4300 (266 MHz), 1024 MBytes, Kingston
Software
Windows Version Microsoft Windows XP Professional Service Pack 2 (Build 2600)
DirectX Version 9.0c
Voilà !
Je vous remercie beaucoup d'avance, étant donné que le problème persiste depuis fort longtemps.