82815 GMCH
R
Datasheet
65
Bit
Description
7:6
Read Power Throttle Control—R/W.
These bits select the Power Throttle Bandwidth Limits for read
operations to system memory.
R/W, RO if Throttle Lock (bit 3 =1). These bits are locked (read-only) when bit 3 (Throttle Lock) is 1.
00 = No Limit
(800 MB/Sec) (Default)
01 = Limit at 87 %
(700 MB/Sec)
10 = Limit at 75 %
(600 MB/Sec)
11 = Limit at 62 %
(500 MB/Sec)
5:4
Write Power Throttle Control—R/W.
These bits select the Power Throttle Bandwidth Limits for Write
operations to System Memory.
R/W, RO if Throttle Lock (bit 3 =1). These bits are locked (read-only) when bit 3 (Throttle Lock) is 1.
00 = No Limit
(800 MB/Sec) (Default)
01 = Limit at 62 % ( 500 MB/Sec)
10 = Limit at 50 %
( 400 MB/Sec)
11 = Limit at 37 % ( 300 MB/Sec)
Note:
These bits must be set to ‘01’ if using 100 MHz system memory and ‘10’ if using 133 MHz
system memory.
3
Throttle Lock—R/W.
R/W, RO if Throttle Lock (bit 3 =1). Once set, this bit can only be cleared by a reset.
0 = Bits [7:3] remain writeable
1 = Block writes to bits [7:3]
2
Reserved—RO.
1
BNR Lookahead—R/W.
This enables the HT unit to look further up the data path to optimize the BNR
(Block New Requests) signal to increase our effective IOQ (In Order Queue) depth.
0 = Normal Behavior (default)
1 = BNR Lookahead Enable
0
Graphics Translation Window Size Select—R/W.
In GFX mode this would be the size of the GTT
(Graphics Translation Table). Not a valid bit in AGP mode.
0
=
64 MB (default)
1 = 32 MB.