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View Full Version : weird idea for performance boost, lower multi, raise fsb


Gator
07-30-02, 08:23 AM
I know, confusing title... but here is my idea:

If you take a 333 capable motherboard and an AthlonXP, unlock the AthlonXP and LOWER the multiplier, but in turn increase the FSB to 166/166, would you see a great performance boost because of the faster data rate?

example:

AthlonXP 1600 = 133 x 10.5 = 1400mhz

unlocked 1600 = 166 x 8.5 = 1411mhz

I figured the advantage of this is you don't overheat the AthlonXP nor do you require extra equipment like water cooling, yet you get the benefits of a faster bus, yes?

What do you all think?

monkeydust
07-30-02, 09:25 AM
Yeah, that's the norm for overclocking unlocked cpu's. Lower the multiplier so you can raise your FSB higher which in turn increases the performance of everything on the bus.

SnakeEyes
07-30-02, 10:27 AM
Absolutely. That's what I did first when I started with my KT3Ultra and my XP2100+. So long as you can maintain the more agressive memory timings, up'ing the fsb synchronously results in better performance, even with a clock speed that is relatively close. Of course, I've also overclocked mine now (1846Mhz from 1729MHz), using a fsb of 161MHz asynchronous (the best tradeoff between agressive memory timings and fsb speed, for my rig.) This took much benchmarking (of video performance, memory performance, processor performance, etc.) to cover all the areas, and repeating for each fsb/memory timing combination I tried, until I was satisfied that I had a decent compromise. I also found that while some of the benchmarks were higher with certain settings, others actually decreased, and system stability wasn't completely tied into the maximum processor MHz NOR the highest fsb. There's some sort of complex interaction between the different possible variables that made it stable at 180MHz fsb synchronous (one successfully tested example) while in another it wasn't with only a 167MHz synchronous.

I spent a few weeks playing with this, as several friends can attest. Ask |wm|crashdump or |wm|pneumatic about all the times they wanted me to come play UT and I just replied that I couldn't: tweaking. :p

|JuiceZ|
07-30-02, 11:38 AM
thats right gator, there's nothing weird about. Outta every mb/cpu I've o'ced, raising the fsb has yielded much better results than just changin' the multiplier because theoretically it o'c everything that runs on the bus. Although the downside is, I've seen a lot more probs with higher fsb too....

NeoGeo
08-04-02, 06:42 PM
if you raise the FSB to say 166, you can get some nice performance, and my board has a choice on how you wanna split the FSB ratio around the system... im at 4:2:1 at the mo... so 33MHz goin to my PCI, 66MHz to my AGP, and 133 to my FSB... the other option is 5:2:1, so if i do raise to 166 the PCI isnt affected at still runs at 33MHz, but the AGP runs at like 83MHz lol... i havent actually got any decent memory so i cant play about much at the mo... but what kinda experiences have people had running their AGP bus so high?

Feanor
08-04-02, 07:49 PM
Do be careful on the memory used though (look around to see what memory OCs better) and also peripherals. Unless one can change the clock ratio between the PCI (as well as AGP) bus and main memory...some cards just do not take well to running at a 41.5 MHz PCI bus... Some gfx cards have been more finicky about AGP clock speed then others as well... Test with memory and peripherals to be sure

TheOneKEA
08-05-02, 12:30 PM
I've read in many places that the 5:2:1 ratio is best for a 166MHz FSB because it keeps the PCI bus at the right speed (from what I've read, stuff on the PCI bus doesn't like to run faster than normal).

Would you need a really good AGP card (nVidia) and some really good DDR memory to run an AGP bus at 83MHz?

Spectral
08-05-02, 03:26 PM
I wish I had the ability to select 5:2:1 on my board... Im stuck with 4:2:1

NeoGeo
08-05-02, 05:01 PM
yeah that sucks on the kr7a, but hey it was never intended for 166 bus usage....