Whats stopping my OC

[NobbyStiles]

Hi.

I'm using an NF7S with 2x256 PC3200 Corsair TwinX RAM and I can't get it to run over 190MHz FSB.

With the RAM at 6-2-2-2 and 2.85v(MBM5) and the CPU at 1.65v(CPUZ) I've tried upping the FSB but using the CPU FSB/DRAM Ratio to keep the memory speed low.

I can run Prime95 stable with the External Clock at 230MHz and a multiplier of 7 (1600MHz CPU) with the memory at 138MHz.

If I try setting the External Clock to 200MHz and the ratio to 4:6 which put the CPU FSB/DRAM Ratio at 133MHz (1470MHZ CPU) Prime95 errors in couple of seconds.

I believe that this shows that the CPU/Mobo is capable of running at 230MHz but the memory is stopping things. So I tried the same thing with 2x256 PC3500 Mushkin Level2 but get exactly the same results.

The only thing which occurs to me is that the Northbridge could be getting too hot so I've ordered a new cooler for that.

Any other ideas why I can't get past 190MHz 1:1 would be appreciated.

 

[Balrog]

Try memory at Auto for voltage and 7-3-3-2.5 timings and always run in sync.

Regards, Balrog

 

[Net-trix]

Agreed with above...

You will see better performance with the memory run in sync. Here are a few other suggestions to get you to your 200FSB.

1) Relax the memory timings to 2.5, 3, 3, 7

2) Increase vcore...this will help stabalize system.

3) Increase chipset voltage to 1.7 (this helps with higher FSB)

4) Increase vdimm to 2.8 (this also helps)

5) check temps! Might be limiting due to temp.

Good Luck!

 

[NobbyStiles]

Thanks for the suggestions.

Tried increasing the chipset to 1.7v with the memory at 2.8v (2.85v in MBM5) and 11-2-2-2 and vcore at 1.8v (MBM5 reading 1.75v). I put the FSB at 200MHz and the multipiler to 7 but Prime95 still errors after about 5 minutes.

I tried relaxing the memory to 11-3-3-2.5 but Windows wouldn't boot.

The temps are high (I think) with the CPU going up to 51 before Prime95 errored. I changed the thermal paste for AS5 recently and think I must have applied it wrong cos I'm using an SLK900 which should be able to keep it cooler than that. I put the same stuff on the Northbridge so maybe that's getting too hot.

Vantec Iceberq chipset cooler in the post so I think I'll clean up the Northbridge and CPU and reapply the AS5 when that comes then try your suggestions again.