Intel Core Duo: AOpen i975Xa-YDG to the Rescue

FSB Overclocking Results

Front Side Bus Overclocking Testbed
Processor:	Intel Core Duo T2400 -1.83GHz
CPU Voltage:	1.400v (1.250V default)
Memory Settings:	4-4-4-15 at 667MHz
Memory Voltage:	2.15v
NB Voltage:	1.575V
PCI-E Voltage:	1.525V
Cooling:	AOpen Supplied Cooler
Power Supply:	FPS FX700-GLN
Maximum CPU OverClock:	255fsb x 11 (2805MHz) +54%
Maximum FSB OverClock:	255fsb x 11 (2805MHz) +54%

Click to enlarge

This board is a very good overclocker although it does have a couple of quirks. The BIOS allows you to overclock the front side bus by 1MHz increments but you are limited at both the minimum and maximum levels by a set of jumpers. If the JP4 and JP5 jumpers are enabled the board defaults to a 166MHz minimum and a 199MHz maximum. If these jumpers are disabled the board defaults to a 200MHz minimum and a 320MHz maximum.

The Core Duo processor does not allow a change to the CPU multiplier so keep this in mind when deciding what CPU to purchase. We were able to take our retail CPU to a setting of 11x262 before we hit a ceiling with either the board or the CPU utilizing the stock cooling. We are reporting our maximum numbers at 11x255, not because of the board or CPU not being stable at 11x262, but due to our comparative Opteron 175 only reaching this level and remaining stable. This board series has reached the 274FSB level based upon user experiences, so we either reached the limit of our CPU or possibly our board does not overclock quite as well as retail samples.

Considering the maximum official Core Duo CPU is currently running at 2.16 GHz, an overclock to 2.882 GHz (using the relatively inexpensive T2400 CPU) is nothing to complain about! We might even add that our retail CPU stayed in the 36c to 39c range under load at the overclocked settings with the AOpen supplied heatsink/fan. Additional testing with a watercooling unit brought our temperatures down to the 26c range under full load as we reached a 267FSB level (required 1.675V on the Nortbridge, 5-5-5-15 memory timings) before the board would not post.

Memory Stress Testing

Memory stress tests look at the ability of the AOpen i975xa-YDG to operate at the officially supported memory frequencies of 667MHz DDR2 at the best performing memory timings the Corsair CM2X1024-6400PRO revision 1.4 will support.

AOpen i975Xa- YDG Stable DDR2-667 Timings - 2 DIMMs (2/4 slots populated - 1 Dual-Channel Bank)
Clock Speed:	166MHz (667FSB)
Timing Mode:	667MHz - Default
CAS Latency:	3
RAS to CAS Delay:	3
RAS Precharge:	3
RAS Cycle Time:	8
Voltage:	1.9V

The AOpen board was very stable with two (1GB) DDR2 modules in Dual-Channel mode at the settings of 3-3-3-8 at 1.9V. The board would set tRAS to 12 if the memory selection was left on auto. We did not notice any issues throughout our testing with a tRAS setting of 8 at the stock 11x166 setting. We will now install our Corsair modules into all four available memory slots, which results in more strenuous requirements on the memory subsystem than testing just two DDR2 modules.

AOpen i975Xa- YDG Stable DDR2-667 Timings - 4 DIMMs (4/4 slots populated - 2 Dual-Channel Banks)
Clock Speed:	166MHz (667FSB)
Timing Mode:	667MHz - Default
CAS Latency:	3
RAS to CAS Delay:	3
RAS Precharge:	3
RAS Cycle Time:	12
Voltage:	1.95V

The AOpen was completely stable with four (1GB) DDR2 modules in Dual-Channel operation at the settings of 3-3-3-12. Note that tRAS had to be changed from 8 to 12 along with a slight memory increase to 1.95V. These are excellent results as the board performed superbly throughout our memory testing regimen that included eight to twenty four hour runs of MemTest86 and Prime95 along with numerous iterations of SuperPI set at 32M. This board along with the Intel 975X core logic is about as solid as it gets.