Seems like my mobile athlon doesn't like high fsb but my Sempron loves it

[Toro 45]

I finally got my Shuttle an35nUltra and an XP-M2400 and put it together last night. Before I installed the mobile I fired up a Sempron 2200(1500mhZ) from a Fry's cpu/mobo $50.00 combo. Also a new stick of Corsair Value select pc3200, the cpu is multi locked so I just kicked it up to 200fsb @1.65v. Another bump to 220 with 1.75v=1980mhz it ran fine. Then up to 230fsb I kicked it around some bechies and prime for a bit. Damn thing went all the way up to 145fsb for 2210mhz, the ram was set at the most relaxed setting, it would run aggressive setting up to 230fsb but did'nt like turbo at most any setting.(not dissapointed in the ram got what I paid for) So not a bad overclock on the sempy 1500mhz stock up to 2200mhz OC= 700mhz

With such an easy OC on the Semperon I figured just slap the mobile in and go to town right? Nope, 200fsb x 10 and prime errors right away I tried a few more fsb's over 200 and would'nt boot etc.(memory on relaxed setting like before) could'nt even come close to the speeds close to what the Semp was doing . So I started turning down the fsb and the ram, 166 x 13 and I was running 2171 no sweat. So I painstakingly spent to next couple of hours trying every frggin fsb multiplier, voltage,combo I could come up with.


I found as long as I stayed in the low 200 on fsb I was able to (208-217) hit up to 2400mhz @1.75V. So overall I'm very pleased with the board and cpu overclock. I'm just a bit confused as to why the sempron was smooth as butter up 245fsb but the mobile hated anything over 217fsb on the same board?

I noticed in the overclocking your mobile thread not all but "most" of the overclcocked cpu's are running the same way, low 200's fsb. I never really expexcted to get much over 220fsb with my ram cpu etc. but that damn sempron got me stoked with the high fsb thinking my mobile was going to was going to run near the same fsb.

 

[Toro 45]

Anyone have any ideas why the Sempron could hit 245fsb while the mobile doesn't like anything over 220fsb with the same ram/timmings and mobo?

 

[broly8877]

less cache

 

[Toro 45]

You might have something there.

 

[AWhackWhiteBoy]

my DFI makes me happy, 248mhz

 

[Toro 45]

Well my shuttle rocks my sempy at 245fsb but no 245fsb, lovin for my mobile

Oh ya and "248mhz" be careful you don't hurt yourself with that one

 

[Avalon]

Not sure why your sempron could take a higher FSB over the mobile. Perhaps you got a lousy mobile and a good sempron. Anyway, I just wanted to comment on your note that you've been seeing most mobile users running with a FSB between 200-220 in that overclockers thread for mobiles. I'm running like that as well, but it's not because of my chip. My motherboard won't do higher than 220 FSB, and I think that's the reason why most others don't go over 220, unless they've got a DFI Infinity/Lanparty or a good NF7-S v2.

 

[Xdreamer]

Originally posted by: broly8877

less cache

i concur

 

[Zap]

Less cache may affect higher overall MHz, though the mobile starting at lower voltage may negate some of that effect. Less cache *should not* affect FSB speed, especially when the mobile chip can have the multiplier reduced so that the CPU is no longer the limiting factor. Also, since the RAM was tested on the same motherboard to 230MHz FSB, that should be the limiting factor.

In this case, what's going on?

Possibility #1 Toro 45 is hitting the limit of his CPU. He said that he's getting 2400MHz at 1.75v. That's pretty good. I had a mobile 2600+ that wouldn't go above around 2400-2450MHz without a huge boost in voltage. With so many people hitting around that speed, perhaps that's the nominal clock speed ceiling of current Barton chips.

Possibility #2 the motherboard runs different latencies based on the "detected" FSB of the chip on the board. To check for this, seriously reduce the multiplier on the mobile chip and try raising the FSB. If the FSB can go higher, then you're CPU limited. If the FSB still cannot go higher, then you'll need to fool the motherboard into thinking the mobile CPU defaults to a different FSB.

 

[AWhackWhiteBoy]

it could simply be the fact that they're two completely different CPU archs. its like comparing apples to oranges.

 

[JBT]

Originally posted by: AWhackWhiteBoy
it could simply be the fact that they're two completely different CPU archs. its like comparing apples to oranges.

Agreed. Also I had always heard Mobile Xp's weren't the best FSB OCers anyways....

 

[Toro 45]

Just to clarify, the ram was doing 245fsb on optimal just fine with the sempron but would only go to 230fsb on the agressive setting(Optimal, Agressive, Turbo, Expert)

The board does adjust the ram latencies to more relaxed settings as you raise the fsb.
Like I said before I'm pleased with my overclock on both chips just a bit stumped as to why one hits 245 and the other 217.

 

[AkumaX]

it could be that the full 512kb in the mobile barton cant handle high fsb (at least for this particular chip)

and since the sempron is newer, they might be using good 25kb cache allowing hi fsb speeds