P4 1.6A vs 1.8A O/C Abilities

[Cooj]

Seems kinda quiet so I'll keep going with my constant questions/banter.

I just noticed that the 1.6A and 1.8A have a price difference of only $20 cdn or $15 us roughly. That's a pretty small price difference for 200 mhz. I've heard that the 1.6A is better for O/C purposes but is that true? If it is by how much?

I'm thinking that I should dish the extra money get a better CPU that way I dont have to push the system as hard.

Cooj

 

[Crashman]

No, they both clock to about the same max, the reason people say it's "better" is because it has a larger percent gain, not a higher top speed. The 1.8A is a better choice because its higher multiplier allows you to keep your bus speeds at a more reasonable rate.

For instance, you can take a 1.6A to 2133 at 133 (QDR533), but the 1.8A would be doing 2400MHz at that speed. You can take the 1.6A to 2400MHz at 150MHz FSB, but beyond that you're getting into some really high bus speeds that some parts might not like. At 150MHz FSB, the 1.8A would be running 2700MHz. Since they both max out at around 2500-2600MHz with stock cooling and reasonable voltages, the 1.8A would be a better choice for these high clocks, again due to the bus speed.

<font color=blue>You're posting in a forum with class. It may be third class, but it's still class!</font color=blue>

 

[chuck232]

Wouldn't the P4 1.6A be better cause you'll have a <i>higher</i> FSB? Also, I'd think that the 1.8A maxes out a bit higher than the 1.6A.

<i>Past mistakes may make you look stupid, but avoiding future ones will make you look smart!</i>

 

[Crashman]

Well, in order for it to offer better performance, you would have to be running PC1066 at PC1200 speed, 150MHz FSB. That's assuming that the 1800 can't reach 2700MHz, same memory speed. Any other memory type/speed can't benifit the processor with higher bus speeds, because the memory then becomes the bottleneck. For instance, running a 1.8A with PC3200 (DDR400) at 133MHz FSB/2400MHz CPU, using the 2:3 FSB:RAM ratio to get the memory to full speed, would return the same results as using the 1.6A at 150MHz FSB/2400MHz CPU, using the 3:4 ratio to get the memory at full speed. In both cases the performance is the same because the memory is the bottleneck at ~3200MB/s. Yes, the 1.8A is known to go just a little higher than the 1600, but I think that's more a matter of bus speed than anything else.

<font color=blue>You're posting in a forum with class. It may be third class, but it's still class!</font color=blue>

 

[Crashman]

Well, in order for it to offer better performance, you would have to be running PC1066 at PC1200 speed, 150MHz FSB. That's assuming that the 1800 can't reach 2700MHz, same memory speed. Any other memory type/speed can't benifit the processor with higher bus speeds, because the memory then becomes the bottleneck. For instance, running a 1.8A with PC3200 (DDR400) at 133MHz FSB/2400MHz CPU, using the 2:3 FSB:RAM ratio to get the memory to full speed, would return the same results as using the 1.6A at 150MHz FSB/2400MHz CPU, using the 3:4 ratio to get the memory at full speed. In both cases the performance is the same because the memory is the bottleneck at ~3200MB/s. Yes, the 1.8A is known to go just a little higher than the 1600, but I think that's more a matter of bus speed than anything else.

<font color=blue>You're posting in a forum with class. It may be third class, but it's still class!</font color=blue>