Gigabyte GA686BXS running slow will not boot until hub is powered



These problems may or may not be connected system seems to be running slower than it used to games that ran fine are suddenly slow and jerky, excel takes an age when calling menus and updating cals test progs like sandra etc show no problems and no significant changes to system.

Things I have noticed
On boot up when the on board scsi adapter configs devices some times the devices may be ASYN or UNK this is random and sometimes they may be all be ASYN or all UNK or various combinations

The system willnot boot anymore unless the hub is powered other 2 machines on LAN do not need to booted and will boot wether the hub is on or off.

First HD average thro put 6MB/s
second HD average 11MB/s Peak 18
third HD 13MB/s - 19
Why is an identical HD so slow as a boot drive plenty of space on it 2gig free
Question does haveing a mix of scsi drives ie scsi2 scsiwide scsiultrawide drop the max speed to the slowest drive even if the is 2 sockets on the mobo? would it be better to fit another scsi controller card for the cddrives and leave the hd on the mobo scsi?

PII 350 (3.5100)
256MB Pc100 ram
Segate ST3940W(68pin highdensity last drive on cable term on)
Plextor 12432 cd-rw (50 pin)
Plextor ultra plex40 max CDROM (50 pin)last drive term on mobo set high byte on
Ls 120 ide prim slave (on board fd disabled and sec hdc disabled
3Com 3C905B-TX 10/100 NIC
3DFX Voodoo3 card
usb Scanner
usb HP 895CXI printer
adaptec AIC 7880 on board scsi
Creative PCI128 sound
Rockwell chipset extmodem