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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johnsonx - Thursday, August 12, 2004 - link
What is it with you people griping about CPU choices? This is a review of current top-end 925X boards, not a CPU review! The FX-53 scores are there only for a point of reference. Added to that, Wesley's point is VERY valid: the 560 and FX-53 ARE the top CPU's from each camp.If you really want to know how a 3800+ would perform, refer to past Socket-939 reviews, or just mentally subtract about 3% or so.
STOP WHINING!
Wesley Fink - Thursday, August 12, 2004 - link
#17 - Since we were trying to determine the maximum overclocking ability of the boards tested, we used a 3.6 ES LGA 775 Prescott at a 14 multiplier (2.8Ghz). The 14x280 is close to 3.9GHz speed. We also checked with a retail 540 (3.2GHz) and reached 250FSB (4.0GHz) at 1.45V.These results lead us to believe that many 775 Prescotts will top out at 3.9 to 4.0GHz on boards that will support those overclock levels. That means that there are likely some 2.8 Prescotts out there that can reach 280FSB.
As always, overclocking is variable, and you need a really great power supply and decent cooling to support the power requirements at these kinds of overclocks.
Carfax - Thursday, August 12, 2004 - link
Wesley, is it possible to do a review of Prescott which focuses on the upcoming 1ghz FSB? I've heard that Prescott scales better than N.W with a higher FSB and greater clockspeed..To do the review correctly, you'd need an engineering sample with an unlocked multiplier, so you can see the benefit of the increased FSB, without raising the clockspeed.
I think Prescott would do pretty well on 1066FSB and with fast DDR2 memory..
danidentity - Thursday, August 12, 2004 - link
Wes,When you say you hit 280 FSB with the Asus P5AD2, was that with a retail chip, multiplier locked? Or were you using an ES chip. If you were using a retail, that is an absolutely insane overclock.
danidentity - Thursday, August 12, 2004 - link
>> Better than comparing a 3500+ to a 3.6F anyway :PHow would a 3500+ compare with a Intel 3.6? Could it hang? :)
RyanVM - Thursday, August 12, 2004 - link
I have no problem with the 3.6E and FX53 being shown together since both platforms will end up costing about the same (factoring in CPU, mobo, and memory costs). Prices fluctuate, yes, but both companies (OK, mainly AMD) tend to adjust prices to stay in line with performance levels (if Intel drops the 3.6E price, I'd put money on AMD dropping prices at the high end within a day or two).Better than comparing a 3500+ to a 3.6F anyway :P
Creig - Thursday, August 12, 2004 - link
#12/#13 Given the way pricing can fluctuate, it would be futile to compare Intel $$$ to AMD $$$. A couple of days after the article was published, pricing could change to make the monetary comparison useless and therefore misleading.I think they're doing it the correct way. It's up to the end user to find his/her best balance between performance and price.
mjz5 - Thursday, August 12, 2004 - link
man, i should of read #12 first before posting it.. why not have an edit button?anyhow, u all know what i'm saying!!!
mjz5 - Thursday, August 12, 2004 - link
the way i see it is that CPUs should be compared by price. If an AMD FX-53 cost as much as a Celeron 2.4 GHz, why not compare the two? If someone is going to looking at these products because they cost X dollars, they aren't interested in seeing that an Intel CPU that cost (X*2) may or not surpass it the competitor at only X dollars.Wesley Fink - Thursday, August 12, 2004 - link
#9 & #10 - Corrected