FIRST LOOK: Asus P5AD2-E - 1066FSB & DDR2-711

Asus P5AD2 Premium: Overclocking and Stress Testing

FSB Overclocking Results

Front Side Bus Overclocking Testbed
Processor:	Pentium 4EE LGA 775 (Gallatin Core) 3.46/3.2GHz
CPU Voltage:	1.55V (default)
Cooling:	Thermaltake Jungle 502
Power Supply:	OCZ PowerStream 520W
Maximum OC at Stock Multiplier:	300x13 - 3900MHz (+12.7%)
Maximum FSB OC:	324FSBx12 (+21.8% Bus OC)

The 3.46EE CPU Intel supplied for testing was unlocked, but the only available multipliers were a stock 13X and 12X. Since the 3.46EE is the only current 1066FSB CPU, this means that options for bus overclocking are limited. However, having said that, we were still able to reach 324FSB at 12X for a DDR2 1:1 memory overclock of 648. Asus also provides an additional memory multiplier of 711 on the P5AD2-E, so we tried out the higher memory frequency with some of the latest OCZ 1GB DDR2 DIMMs rated at 3-2-2-8. This memory ran great in the P5AD2-E and also allowed us to reach DDR2-750 with a modest overclock at the DDR711 setting.

The P5AD2-E provides the best overclocking that we've seen on an Intel 925XE/925X board, although the Abit Fatal1ty AA8XE, based on the same 925XE xhipset, reaches virtually the same levels in overclocking. The 711 multiplier for memory opens new options for memory overclocking that are unique to the P5AD2-E.

Memory Stress Test Results:

The memory stress test measures the ability of the Asus P5AD2-E to operate at its officially supported memory frequency (533MHz DDR2), at the best performing memory timings that Crucial/Micron PC2-4300U will support. Memory stress testing was conducted by running DDR2 at 533MHz (stock 1:1 ratio) with 2 DIMM slots operating in Dual-Channel mode.

Stable DDR533 Timings - 2 DIMMs (2/4 DIMMs - 1 Dual-Channel Bank)
Clock Speed:	266MHz
Timing Mode:	1:1
CAS Latency:	3.0
Bank Interleave:	Auto
RAS to CAS Delay:	3
RAS Precharge:	3
Cycle Time (tRAS):	10*
Command Rate:	N/A

*SPD (Auto) timings for DDR2 are normally 4-4-4-12 at DDR2-533. A tRAS setting of 12 is normal. We ran a series of tests to measure memory bandwidth, and found the tRAS setting made very little difference in the performance of DDR2. The most effective range of tRAS was 8 to 13 for DDR2 on the 925X chipset, so a tRAS of 10 was chosen for benchmarking.

The Asus P5AD2-E was completely stable with 2 DDR2 modules in Dual-Channel at the settings of 3-3-3-10, at 1.8V default voltage. Intel has updated memory timings on the 925XE series boards and now specifies 3-3-3 as default timings compared to the 4-4-4 timings specified at the 925X/915 launch.

Filling all four available memory slots is more strenuous on the memory subsystem than testing 2 DDR2 modules on a motherboard.

Stable DDR533 Timings - 4 DIMMs (4/4 DIMMs - 2 Dual-Channel Banks)
Clock Speed:	266MHz
Timing Mode:	N/A
CAS Latency:	4.0
Bank Interleave:	N/A
RAS to CAS Delay:	3.0
RAS Precharge:	10T*
Precharge Delay:	3.0
Command Rate:	N/A

As we first saw in the 925X roundup, four DDR2 DIMMs are not stable at CAS 3 as 2 DIMMs are. We required 4-3-3 timings when using 4 DDR2 DIMMs, though the 4-3-3 timings did work fine at default voltage.