Telling wether MB or CPU is failing @ 400mhz FSB

ginjaninja · 19 Dec 2007 at 16:52

i have asus maximus formula
q6600 g0
dominator 8500c5

everythings seemed ok when increased the FSB to 400..cpu @ 3.6 all bios on auto. however prime95 will sometimes fail a few hours into cycle. (the machine just reboots).

if i set the multiply to 6. would this confirm wether it was the board or the cpu that had the problem with 400 mhz..or would that not be an exact science....i think its the board becuase things like coretemp and asus probe often have problems reading voltages temps.

Typhoon · 19 Dec 2007 at 17:04

ginjaninja said:
all bios on auto.

That will be the fist thing I'd play with. I have had Core 2 cpus with lowish FSB walls, would go past 380FSB whatever you did to it.

pendulum666 · 21 Dec 2007 at 15:58

Interesting. Your theory about lowering the CPU multi was exactly what I would have said to do. I have the same problem in a P35-DS3r mobo running a e2140. I can hit 400x8 = 3.2ghz with good temps, and its stable for hours in Orthos. Memory passes mem test and works fine under that cpu clock as well. But when I go to raise it anything over 400 FSB despite having low CPU multi, it just won't boot at all.

Is there a relationship between vcore and high FSB? i..e You have a cpu you know hits 3.2ghz @ 1.4V say, but even when lowering the multi decreasing the clock speed, the high FSB needs more vcore? I thought FSB stability was more related to FSB Voltage control (Northbridge/chipset voltage) and other things. Thought vcore was ONLY related to cpu stability?

Pneumonic · 21 Dec 2007 at 16:09

you could try setting your PLL voltage.. dont really no a huge great deal about this but basically is the link between the FSB and CPU.. setting it @ 1.6v rather than leaving it on auto allows my rig to boot at high FSB than usual for suiside pi runs etc... this is on a P5K-E not sure what its called on other boards

Fr0dders · 21 Dec 2007 at 16:18

as above

C2Ds are multiplier unlocked downwards

lower the multiplier, but then increase the FSB to achive the same clock as you've already got

if its stable, then its your CPU that wont overclock any more

If its not, then you've hit the FSB wall, which could be CPU or motherboard, as they both have their own limits.

ginjaninja · 31 Dec 2007 at 10:40

looks like the crashing (reboots) was due to overzealous overheat protection in bios..have disabled now and its happy at 400x8 with case closed and 400x9 with case open.need to improve case cooling i think. going to try to increase fsb from 400x8 towards 450x8....i can achieve an insanely low vcore of 1.16 for 400x8 (which is why i can run with case closed as the air flow is removing enough heat from case ..but not at 400x9 with a prime 95 heat test.)