Intel 925X Roundup: Creative Engineering 101
by Wesley Fink on August 12, 2004 12:05 AM EST- Posted in
- Motherboards
Abit AA8: Overclocking and Stress Testing
FSB Overclocking Results
| Front Side Bus Overclocking Testbed | ||
| Processor: | Pentium 4 Prescott LGA 775 2.8GHz |
|
| CPU Voltage: | 1.3875V (default) | |
| Cooling: | Thermaltake Jungle 502 | |
| Power Supply: | HiPro 470W | |
| Maximum OC: | 260FSB (+30%) | |
Like the earlier Socket 478 Pentium 4 processors, the LGA 775 CPUs are multiplier locked. Therefore, the only way to overclock the CPU is to increase the FSB. Unfortunately, the PCI Express bus is not locked, or rather, fixing the frequency tends to limit the overclocking of the 925X. Abit manipulates the PCIe frequency with µGuru during boot to achieve higher overclocks. For more information on how Abit manages to overclock the AA8, please check Breaking Intel's Overclock Lock: The REAL Story.
The AA8 was able to achieve a reach for FSB of 260, a 30% overclock, with an ATI X800 XT and SATA hard drive. Abit was able to achieve close to the same overclock with the nVidia 6800 Ultra at 258. The nVidia is generally less tolerant of out-of-spec PCIe frequency, so this performance is really excellent.
Memory Stress Test Results:
The memory stress test measures the ability of the Abit AA8 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 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 |
The Abit AA8 DuraMAX was completely stable with 2 DIMMs in Dual-Channel at the DDR2 settings of 3-3-3-10 at 1.8V default voltage. These are much faster settings than the DDR2 SPD and rated timings of 4-4-4-12.
Filling all four available memory slots is more strenuous on the memory sub-system 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: | 3:4 (200:266 - Default) |
| CAS Latency: | 4.0 |
| Bank Interleave: | Auto |
| RAS to CAS Delay: | 3 |
| RAS Precharge: | 3 |
| Cycle Time (tRAS): | 10 |
| Command Rate: | N/A |
DDR has a long benchmarking history that makes it easier to figure out where to go with memory timings. We are still in the learning curve with DDR2, and the old DDR patterns just do not work in DDR2. We found that no matter what the rest of the settings, 4 DIMMs with DDR2 required CAS 4 for stability. Timings like 3-4-3 or 3-4-4 appeared to work fine, and then we were suddenly facing hard drive corruption. Our advice for now is to use CAS 4 with 4 DIMMs for stability, although 4-3-3 timings did work fine on many of the test boards. If you plan to try raising voltage to attempt lower CAS with 4 DIMMs, then please backup your system first. Our test beds gave no warning at all before hard drive corruption with overly aggressive timings using 4 DIMMs.
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jdoor0 - Tuesday, October 26, 2004 - link
This review has been reviewed:http://www.theinquirer.net/?article=18896
Nige - Tuesday, October 12, 2004 - link
Does the ASUS P5AD2 Deluxe motherboard have the same overclocking capability as the P5AD2 Premium?skiboysteve - Friday, August 13, 2004 - link
Wow nice catch. i guess my "(I know... toms sucks)" disclaimer came true.yaeh i understand.
Wesley Fink - Thursday, August 12, 2004 - link
#26 -There is now an apology to Asus up at THG. They measured the voltage wrong. We had also measured the voltage and found 1.5 to 1.55 which is well within spec, not 2.1 as they reported. They now acknowledge the correct voltage measurement for the P5AD2 is 1.53V.
High Northbridge voltage is not the reason the Asus, or any other 925X/915 board, overclocks well. There are far too many simple and wrong explanations for the complex overclocking issues of the 925X/915 chipsets.
skiboysteve - Thursday, August 12, 2004 - link
Page 10"...Broadcom attached to the faster PCI Express bus..."
there is no PCI Express bus, its a point to point protocal.
Just nitpicking.
Great review.
Also, over at Toms (I know... toms sucks) they looked at 9x5 Boards over there and showed that the Asus P5AD2 was running at an astounding 2.1v on the northbridge (1.5v is the stock)
Something might have to be mentioned about reliability of such out of spec behavior, and cooling concerns. You might want to conduct your own quick test on the voltage with a multimeter.
broberts - Thursday, August 12, 2004 - link
One of the problems with these arguments is that the FX-53 is almost 20% more expensive.I've been thinking for a while now that benchmarks should show some form of pricing index so that one can better judge the advantage/disadvantage of the various choices. Just quoting prices isn't ideal, for a host of reasons. I'd suggest, instead, a relative measure. And not just the cost of the particular component being benchmarked. Calculate the cost of the each system used in the benchmarks. Pick one, perhaps the lowest or highest cost one and calculate the relative difference in price. I suggest using the entire system because quite often the choice of one component dictates the available choices for other components. Ideally a relative measure for both the components and entire system would be calculated and published.
manno - Thursday, August 12, 2004 - link
Moo Moo MOO.manno - Thursday, August 12, 2004 - link
why no Doom3?Wesley Fink - Thursday, August 12, 2004 - link
#21 -We will definitely be including Doom 3 benches in future reviews. The only reason they are not included in this 925X roundup is because most of the testing was completed before we had a working copy of Doom 3. You can get a clear idea of how the 925X/Intel 560 performs in Doom 3 in Anand's Doom 3: CPU Battlegrounds review published August 4th at http://www.anandtech.com/cpuchipsets/showdoc.aspx?...
kherman - Thursday, August 12, 2004 - link
Umm, Doom 3 benches?