P5B Deluxe: higher FSB lower performance?

[catchsomezz]

8. P5B BENCHMARKS SLOWER AT HIGHER SPEEDS: BleedinEdge member Tony has an in-depth analysis of why higher FSBs can benchmark significantly slower memory bandwidths than much lower ones. For example, in his studies, he systematically proved that a 400MHz FSB is just as fast as a 460MHz FSB on this motherboard, and that a 400MHz FSB can deliver 500MB/s MORE memory bandwidth than just a one megaherz increase to 401! This issue, put simply, relates to the way the chipset (Which is like a very simple CPU) clocks itself based off your FSB with internally-set (And indirectly-controllable) multiplier. Essentially speaking, AVOID A 360-399MHz, 401 and 401-460MHZ FSB AT ALL COSTS. If you intend to overclock, get PC2-8000 and push for 475+ for high CPU clocks, or settle with a 400x6/7/8/9 clockspeed depending on your CPU for maximum performance. Not following these guidelines will not only rake your memory bandwidth over the coals, but also introduce SEVERE instabilities as the chipset (Northbridge) tries to run at too great a clockspeed.

Taken from: http://icrontic.com/forum/showthread.php?t=50712


I just found this, the post was from a long time ago (2006), but is there still any truth in that?

 

[catchsomezz]

bump

anyone...

 

[Evilsizer]

right well it works like this for each section of fsb's there is a Northbridge strap. there strap uses latency timings just like ram to help get higher fsb's. you are talking the first core 2 supported chipset now. P965 switches to a different strap in the 400mhz area, P35 does it at 500mhz. P45 well i havent seen any one report anything yet on it. yes the NB timings can really effect performance, in the case of P35. at 499mhz its using the 266fsb strap and offers higher memory bandwidth then even 500mhz. as at 500mhz like i said it switches to another strap. last time i looked at the numbers even using a fsb at 480mhz had higher memory bandwidth then a fsb at 525mhz on p35 board.

basicly yes there is truth in it...

 

[catchsomezz]

right well it works like this for each section of fsb's there is a Northbridge strap. there strap uses latency timings just like ram to help get higher fsb's. you are talking the first core 2 supported chipset now. P965 switches to a different strap in the 400mhz area, P35 does it at 500mhz. P45 well i havent seen any one report anything yet on it. yes the NB timings can really effect performance, in the case of P35. at 499mhz its using the 266fsb strap and offers higher memory bandwidth then even 500mhz. as at 500mhz like i said it switches to another strap. last time i looked at the numbers even using a fsb at 480mhz had higher memory bandwidth then a fsb at 525mhz on p35 board.

basicly yes there is truth in it...

so im sitting at 455 fsb. should i, for all that is holy, try to push my way to 475? or is it just not worth the (possible) gain

 

[Massive]

strange that it is really happened
Running my proc @400x9=3,6Ghz is faster than 450x9=3,6ghz in 3dmark06 on my DFI DK P45 T2RS.

its a different scenario on my previous P35 (ABIT IP35), higher FSB mean higher result in 3dmark, because I always used the same RAM setting.

 

[DEZMOND]

Try the p965 strap tweak tool.

http://www.waffenss-inc.com/zz-wss/P965StrapTweaker.zip

 

[Evilsizer]

so im sitting at 455 fsb. should i, for all that is holy, try to push my way to 475? or is it just not worth the (possible) gain

thats completely up to you and you goals for the system/oc/performance.

strange that it is really happened
Running my proc @400x9=3,6Ghz is faster than 450x9=3,6ghz in 3dmark06 on my DFI DK P45 T2RS.

its a different scenario on my previous P35 (ABIT IP35), higher FSB mean higher result in 3dmark, because I always used the same RAM setting.

well i know there is a issues with a certian 3dmark program. that the higher the oc on the cpu the lower the cpu score, yet the gpu scores go up. i would run other programs, double check in the bios the fsb strap your running.

Dez,
good find, i have never seen that before for P965.