Nvidia NFORCE 650I - Manual (Page 12)

Mainboard nForce 650i Ultra
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How to enable Dual-Channel DDRII:
1. The mainboard provides Dual-Channel functionality for the four DIMM sockets. Enabling
Dual-Channel will significantly increase your data access rate than the before. DIMM0
and DIMM1 share one channel, and DIMM2 and DIMM3 share another channel.
2. To enable Dual-Channel, you need to install memories in different channels of DIMM
sockets. According to the definition by Intel, once one channel of the memory capacity
is the same with the other channel, the Dual-Channel will be enabled then.
For example, if you install one 256 MB memory in DIMM0 and another in DIMM1 (256MB
x 2 = 512MB), you must install a total of 512 MB memory in DIMM2 or DIMM3, so that the
Dual-Channel can be enabled.
3. If you only need to install one memory, it is recommended to install it in DIMM0 or
DIMM1.
Memory Installation Steps:
1. Pull the white plastic tabs at both ends of the slot away from the slot.
2. Match the notch on the RAM module with the corresponding pattern in the DIMM slot.
This will ensure that the module will be inserted with the proper orientation.
3. Lower the RAM module into the DIMM Slot and press firmly using both thumbs until the
module snaps into place.