AOpen AP53 Betriebsanweisung PDF herunterladen (Seite 2)

Frequently Asked Questions

B-2

Q: Why the AOpen mainboards (MB) do not have cache module expansion

slot?

A: Faster CPU speed requires more difficult and complex MB timing design.

Every trace and components delay must be taken into consideration. The

expansion cache slot design will cause 2 or 3ns delay in PBSRAM timing,

and the extended trace length to the cache module through the golden finger

will further delay the timing by 1 or 2ns. This may result in unreliable system

once the cache module and slot becomes worn. All AOpen MBs support

512KB PBSRAM onboard. For better performance (around 3% higher than

256KB), we strongly recommend you to use 512KB onboard. Otherwise,

reliable 256KB is better than unreliable 512KB with cache module. AOpen is

the first company to promote this concept since the fourth quarter of 1995.

Q: Why do AOpen MBs have two regulators onboard?

A: Heat dissipation becomes a big problem when CPU speed increases. New

generation CPUs use lower voltage or split power plane to reduce power

dissipation. If you use dual-power PP/MT (P55C) CPU, then you need

separate requlators for 3.3V CPU io voltage and 2.8V CPU core voltage.

Refer to section 2.2 "Jumper Settings" for voltage of current CPUs available

on the market. Theoretically, the more regulators, the more reliable power

becomes. For VX chipset MB (AP5V), we even incorporated a third requlator

to support SDRAM. AOpen fully supports PP/MT and SDRAM in its product

line and this puts them ahead among other companies. There is one

exception, ATX MB may use 3.3V power from ATX power supply, it is

possible to reduce one regulator.

Q: What is the difference of Linear Regulator and Switching Regulator?

A: Switching regulator turns on/off Power FET with very high frequency and

uses L/C charge and discharge circuit to do voltage drop. The efficient is

better but voltage ripple and EMI noise is higher. The reason for mainboard

designer to consider switching regulator, is simply because they are worry

about linear regulator can not fully support the coming new CPU. Actually,

this depends on the design and layout quality of mainboard manufacturer.

According to AOpen RD's testing, Intel PP/MT-233, AMD K6-166/200/233

are all fine on AP5T to run winstone97. (The CPU is at 53 degree C, heatsink

is at 60 degree C and regulator IC is at 79 degree C). But for future CPU

(perhaps CPU of 1998), AOpen will still consider to phase-in switching

regulator on new version mainboard.

Q: What is MMX?

1 2 3 4 5 6 7 8 9

Keine Kommentare

AOpen AP53 Betriebsanweisung Seite 2