915 Motherboard Roundup: Socket 775 for the Rest of Us

Epox 5epa+: 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:	223x18 (4014MHz) +12%
Maximum FSB OC:	254FSB x 14 (+27%)

The 5epa+ is a better-than-average overclocker among 915 boards. It is not, however, the top level overclocker that we were hoping for. Above a 254 setting, SATA drives just disappeared, but the Epox continued to go through the pre-HD boot phase to 270 and even higher. This leads us to suspect that the Epox 5epa+ may actually reach even higher overclocks with IDE hard drives. At the stock 18x ratio, the Epox reached 4Ghz, but the CPU heatsink became quite hot in a very short time. For overclocks above around 3.9GHz, you really need better cooling with any of these 915 boards.

Manually selecting PCIe speeds had allowed us to reach higher overclocks on the MSI, so we tried the same technique on the Epox. We still couldn't break though 254 using SATA hard drives. It would be wrong to leave the impression that the highest FSB is a holy grail in our overclocking tests. To put the 254 FSB setting in perspective, this would represent DDR508 at a 1:1 memory ratio. This is an easily achieved overclock with fast memory timings and most current DDR400 memory based on Samsung TCCD chips. Some better TCCD memory on Brainpower DIMM PCBs can achieve DDR550 to DDR580 at reasonably fast timings. At 1:1 ratio, this would be a FSB setting of 275 to 290.

The question with overclocking is always where the trade off occurs. In this case, we have tested Crucial Ballistix DDR400 that does 2.5-2-2 at DDR500. So to run at DDR500 at the fastest speed that our CPU can achieve (about 4Ghz), we would need to run at 250 x16. We can actually run those settings with the unlocked ES 3.6GHz Prescott, but current Intel Socket T (775) processors can run at default ratio or 14X.

Memory Stress Test Results:

The Epox 5epa+ was designed to run DDR400 memory. The memory stress test measures the ability of the 5epa+ to operate at its officially supported memory frequency (DDR400), at the best performing memory timings that OCZ PC3200 Platinum Rev. 2 will support. Memory stress testing was conducted by running DDR at 400MHz (stock 1:1 ratio) with 2 DIMM slots operating in Dual-Channel mode.

Stable DDR400 Timings - 2 DIMMs (2/4 DIMMs - 1 Dual-Channel Bank)
Clock Speed:	200MHz
Timing Mode:	1:1 (200:200 - Default)
CAS Latency:	2.0
Bank Interleave:	Auto
RAS to CAS Delay:	2
RAS Precharge:	2
Cycle Time (tRAS):	5

The Epox ran a single dual-channel (2 DIMMs) at the most aggressive 2-2-2-5 timings at default voltage. The 5epa+ was completely stable at these timings at the default 2.6V.

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

Stable DDR400 Timings - 4 DIMMs (4/4 DIMMs - 2 Dual-Channel Banks)
Clock Speed:	200MHz
Timing Mode:	1:1 (200:200 - Default)
CAS Latency:	2.0
Bank Interleave:	Auto
RAS to CAS Delay:	2
RAS Precharge:	2
Cycle Time (tRAS):	5

When all 4 DDR slots are filled, the Epox matched the performance of the top DDR boards in the roundup, running with stability at the same 2-2-5 timings that worked well with 2 DIMMs.