Originally posted by hitechjb1
939 Winchester 3000+ vs 3200+
One can run the memory bus frequency slower than the HTT with minimal impact on memory performance,
for example, assume bios only has 1:1, 5:6, 2:3 memory_HTT_ratio
For 3000+, max multiplier = 9, memory_divider available = 9, 11,
For 3200+, max multiplier = 10, memory_divider available = 9, 10, 11, 12, 15
So if the CPU clock frequency is 2500 MHz,
one would get memory at 277 or 227 MHz with a 3000+ (x9 max),
one would get memory at 277, 250, 227, 208, 167 MHz with a 3200+ (x10 max).
As can be seen, the 3200+ provides more flexible matching of memory frequency for given memory modules. In addition, one can also get a high CPU overclocking in case the motherboard and system cannot handle high HTT for whatever reason. Say, if HTT is stuck under 260 MHz, with a 3200+, one can still get 2.60 GHz with the x10 multiplier, but with a 3000+, the highest CPU overclock would be limited to 2.34 GHz.
On the other hand, in terms of budget and price-performance, one can argue that a 3000+ is a better choice. Which CPU can potentially give higher overclocking is a luck of draw, due to random nature over the stock frequency specification.
The above argument assumes CPU's are from similar week/stepping. In many cases, newer CPU (more recently dated) may be preferred, especially if supported by results and statistics, probably due to some process, yield improvements or some not-yet-known reasons.
Overclocking setting for various bus frequencies (post 8)
Relationship between CPU_memory_divider and CPU_multiplier, memory_HTT_ratio
How to determine memory bus frequency (post 60)
Memory bus frequency setting, SYNC/ASYNC mode
939 Winchester 3000+/3200+ vs 3500+
3000+ is rated at 1.8 GHz, 3200+ is rated at 2.0 GHz, 3500+ is rated at 2.2 GHz for the 90 nm 939 CPU's.
Statistically, a 3500+ should be overclocked slightly higher than a 3200+, due to the frequency distribution of the 3500+ is centerd higher than that of the 3200+, but they overlap. Depending on the process maturity and yield, that difference can be pretty small, and getting smaller when the chip process matures as the two distribution overlap to a greater extent. Also the small statistical difference may not justify for the higher price of the 3500+ in terms of MHz/$.
Further, since most of us only get 1 or very few such CPU, randomness plays more than the statistical behavior of large samples, so there is no guarantee that a 3500+ one get can be clocked higher than a 3200+/3000+, when they are overclocked few hundred MHz above their rated clock frequency.
In order to make decision, one has to rely on certain objective.
1. If the objective is the highest frequency (even just 1 MHz) at rated frequency, regardless of price, then a 3500+ would have 100% certainty at rated frequency which is 2200 MHz over a 3200+ which is rated at 2000 MHz (assume both CPU are not defective, otherwise can return them). The 3500+ would be the choice.
2. But if the objective is now changed to highest overclocking frequency to a few hundred MHz over rated frequency, then the 3500+ still have a slightly higher probability than a 3200+. But that percentage is small. There is no guarantee that a single 3500+ can be overclocked higher than a single 3200+ at the 2500-2600 MHz level, unless one is dealing with a large sample of 3500+ and 3200+.
3. Now most people when selecting computer/component, a common metric is price/performance, or incremental price/performance.
Lets assume a 3500+ can be overclocked 100 MHz higher (may not be the case).
E.g. (price may not be up-to-date, for illustaration only)
- 3200+ $200 overclocked to 2500 MHz, $0.08 / MHz
- 3500+ $300 overclocked to 2600 MHz, $0.115 / MHz which is 44% higher in price/performance measure.
The incremental price/performance for an overclocked 3500+ would be $100/100 MHz or $1/ MHz !!! (very high)
For price-performance wise, it would be suggested to save that $100 for better memory, or for gaming, more importantly, a better video card.
939 vs 754 Performance (with same L2 size)
http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=2249&p=1
The above article also has a section comparing a 130 nm 939 3800+ and a 130 nm 754 3400+, both running at 2.4 GHz, both has 512 KB L2. It gave the 939 dual channel CPU a few % average performance advantages over the single channel CPU on different kinds of programs, including A/V encoding (4.4%), games (6.3%), video creation/photo editing (4.2%), 3D rendering (5.4%), multi-tasking content creation (3.2%), business/general use (5.4%) applcations. For workstation test, the 939 was ahead by as much as 17%.
Performance analysis of various A64 systems (including Barton, P4's) (post 7)
