Chapter 11: Expansion Cards^249
Dealing with Choke Points
A choke point is a point in the system hardware or configuration where too much data is
trying to get through too small of a passageway or it is trying to move through a point too
fast. One common cause for a choke point occurs when a completely functional but inap-
propriate expansion card is used. For example, using an ISA video card on a Pentium III PC
will likely cause a choke point when the graphics attempt to run over the low-speed ISA
bus.Thesystemwillwork,butitmaybeveryslowandnothavethequalityyou’dexpect.
Ifanexpansioncardisperformingpoorlyorveryslowly,theproblemcouldverywell
be a choke point caused by too much traffic on a bus. This is rarely an issue with a PC
purchased from a reputable dealer or manufacturer.
Some things you can do to prevent or eliminate a choke point for peripheral devices
and expansion cards are Upgrade the motherboard to one with built-in controllers for the floppy disk,
hard disk, and as many other devices as possible to eliminate controllers and
adapter cards on the expansion bus.
If one is not available on the motherboard, install a USB or IEEE 1394/FireWire
port expansion card and use it to add future peripheral devices where possible.
Try using one of the USB devices that provides additional serial and parallel
ports; this can save expansion bus slots.Resolving Resource Conflicts on Windows PCs
If a PC has system resource conflicts, it will let you know in one of the following ways: The system fails to boot and sounds or displays an error beep code or error
message indicating an error on the motherboard or expansion bus.
During the boot sequence, the system freezes u pand will not com plete the boot.
The system halts or freezes up for no apparent reason during an I/O operation
or when an application program is running.
An I/O device performs erratically or intermittently.Theonlycauseforresourceconflictsisarecenthardware(andinextremelyrarecases,
software) upgrade. If the answer to any one of the following questions is yes, then it is
very likely that the PC’s problem is a system resource conflict: Has a new internal device, expansion card, or device driver been recently
added to the system?
Did the error first appear after a new component was added to the PC?
Was the PC operating okay before a new component was added?