915 Motherboard Roundup: Socket 775 for the Rest of Us

Asus P5GD2 Premium: Overclocking and Stress Testing

FSB Overclocking Results

Front Side Bus Overclocking Testbed
Processor:	Pentium 4 Prescott LGA 775 560 ES (2.8GHz-3.6GHz)
CPU Voltage:	1.425V (1.3875V default)
Cooling:	Thermaltake Jungle 502
Power Supply:	OCZ Power Stream 520
Maximum CPU OverClock:	227x18 (4086MHz) +14%
Maximum FSB OC:	279FSB x 14 (+40%)

Asus has fully implemented Speedstep in their recent BIOS updates for the P5GD2 Premium, so the OC results are a lot more than academic - at least on this board. Speedstep means that the stock multiplier and a 14X multiplier will be available on all Prescott CPUs, opening new options for overclocking regular Intel Prescott chips.

You will also be extremely pleased with with the overclocking ability of the P5GD2. The stock multiplier overclock of 227x18 or 4086MHz is the highest frequency ever reached with this 3.6GHz Prescott. The 40% FSB overclock achieved at the 14X multiplier is also the highest OC that we have seen with a SATA drive on a Socket T board. Asus has implemented their magic in the Auto setting for PCI Express and this is the setting used for these overclocks. If you are interested in how Asus manages to reach such an outstanding overclock with the P5GD2, please check Breaking Intel's Overclock Lock: The REAL Story.

The fact that Asus manages a higher OC than more recognized OC boards like DFI and Abit is testament to the solid engineering that went into the P5GD2 design. Stack Cool and the other overclocking enhancements on the P5GD2 Premium apparently do a good job of extending the OC range on the Asus.

Memory Stress Test Results:

Memory stress tests look at the ability of the Asus P5GD2 premium to operate at the 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 3:4 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:	3:4 (200:266 - Default)
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 that 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 P5GD2 Premium was completely stable with 2 DDR2 modules in Dual-Channel at the settings of 3-3-3-10 at 1.8V default voltage. This matches the best timings that all the motherboards in this roundup were able to achieve with DDR2 memory. 3-3-3 is also faster than the 4-4-4 timings specified for the Crucial/Micron DDR2 modules used for these benchmarks.

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 on the Abit, 4 DDR2 DIMMs are not stable at CAS 3 as 2 DIMMs are. Once again, we required 4-3-3 timings when using 4 DDR2 DIMMs, though 4-3-3 worked fine at default voltage. Perhaps more voltage could improve stability at 3-3-3 with 4 DIMMs. We were able to achieve the stability at 2.0V (from default 1.8V) to complete Super Pi and Aquamark 3 at the 3-3-3 timings with 4 DIMMs.