Functional Operation Of Overdrive; Processor Signals - Intel PENTIUM PRO Manual

E
0.80
Max Component
Height on front
of VRM PCB
1.8
Total space
for VRM /
Header 8
from
motherboard
0.550 MIN
Minimum distance to VRM
components from motherboard
NOTE: The connector comprises a header mounted on the motherboard and a receptacle on the edge of the VRM PCB.
Figure 50. OverDrive
8.3. Functional Operation of
OverDrive ®

Processor Signals

8.3.1. FAN/HEATSINK POWER (V
This 5 V supply provides power to the fan of the
fan/heatsink assembly. See Table 33 for V
specifications.
8.3.2. UPGRADE PRESENT SIGNAL (UP#)
The Upgrade Present signal is used to prevent
operation of voltage regulators providing a potentially
harmful voltage to the OverDrive processor, and to
prevent contention between on-board regulation and
the OverDrive VRM. UP# is an open collector output,
held high using a pull-up resistor on the motherboard
tied to +5 Volts.
PENTIUM® PRO PROCESSOR AT 150, 166, 180, and 200 MHz
0.14
Max Component
Height on back
of VRM PCB
2.4
Total height
from
motherboard
to an
immovable
object
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AAAA A
AAAA A A
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AAAA A
0.550 REF
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DIMENSIONS IN INCHES
® Voltage Regulator Module Envelope
5)
CC
5
CC
3.10 Max VRM PCB Width
OverDrive
0.090 REF
There are several system voltage regulation design
options to support both the Pentium Pro processor
and its OverDrive processor. The use of the UP#
signal for each case is described below:
•
Case 1: Header 8 only
If the system is designed with voltage regulation
from the Header 8 only, then the UP# signal
must be connected between the CPU socket
(Socket 8) and the VRM connector (Header 8).
The Pentium Pro processor VRM should
internally connect the UP# input directly to the
VRM OUTEN input. If the Pentium Pro
processor is replaced with an OverDrive
processor and the OEM VRM is NOT replaced
with the OverDrive VRM, the original voltage
regulator will never enable its outputs because
the lower voltage OverDrive processor could be
damaged. Refer to Figure 51.
R
VRM PCB
HEADER 8
3.00 REF
85