When I put the FSB up, the CPU clock goes down?

Hi

I've got an opteron 165. At the moment it's running at stock speeds because when I put the FSB up, the clock speed goes down and I can't understand why.

At the mo it's running at 1800Mhz (200 x 9). If I put the FSB up and change nothing else, say to 245Mhz (245 x 9 should be 2205Mhz) but in reality it changed it to 1200Mhz (Confirmed by CPUZ and PC Wizard).

I'm running it on an Asus A8N-SLI SE. Could it be something to do with me having 4 sticks of RAM in it?

Any help would be appreciated.

Thanks

Have you set the 4 sticks to run @ 2T?? (CPC to disable)

Have you manually set the divider in the BIOS and set CoolnQuiet and CPU Thermal Throttling to off?

Sounds like Cool'n'Quiet kicking in?

Hey

Cool'n'Quiet is set to off.

What do you mean about 2T and CPC? The RAM timings?

I didn't manually set the multiplier...i thought it was locked at 9x

I had an issue with my bro's 146 on an asus MR8-MVP (?) where upping the fsb would down the multiplyer. I believe it's because the motherboard does not lower the LDT or HTT multi.

eg. FSB = 200 CPU, Multi = 9, LDT or HTT Multi =5x, therefore

cpu speed = 1800Mhz, HTT speed = 5x200 = 1000

Now alot of motherboards do not like it when the HTT speed goes over 1000 so you need to drop the LDTor HTT Multi to a safer value liike 3x when upping the FSB.

so for your setup

manually change the LDT or HTT Multi to 3
manually set your CPU Multi to 9
up FSB steadily

so at a FSB of 245 you will have a CPU speed = 9x245 = 2205 and an HTT speed = 3x245 = 735

I would also advise you to put your ram on a divider to start with so the FSB is greater than 200 but your ram runs at 200. Iirc Asus have a % value for the FSB/Mem divider so try something like 4/5 (80%) to start with.

Right, I've set it up as follows:

HTT = 3x
FSB 240Mhz
Multiplier = 9x
RAM = 333Mhz
PCI = 33.33Mhz
Core Voltage = default

and I've got it to 2160Mhz.

As soon as I try 245Mhz FSB it won't post. Does the first bit when it's detecting the hard drives and what not, but not the second bit with the table at the top and the hard drive sizes, cache, etc.

Should I increase the core voltage? I've got a Freezer 64 Pro strapped to my Opteron and it runs at 34 degrees load

Try dropping the ram to a lower divider so as to ensure that it is taken out of the equation. So use a setting of say 50%. You can always increase this later.

See if the booting problem is the same. If it is it will mean that your chip has reached it's limit with the default voltage. So now up the voltage to the next increment/setting and reboot. Keep an eye on your cpu's temperature - you can do this in the bios. Run some benchmarks to ensure that the cpu/machine is stable.

45C is no problem under load for these chips. Post back with results including voltage

Looks like it was the RAM being a gimp. I put it down to 200Mhz and now the FSB is up to 255Mhz :)

I'm running 2 different types of RAM in it:

http://giveitrizz.com/hexus/ram1.gif
http://giveitrizz.com/hexus/ram2.gif
http://giveitrizz.com/hexus/ram3.gif
These are Twinmos PC3700

UPDATE:

Got the FSB up to 275Mhz and the RAM to 266Mhz and all seems stable at the mo. Going to run prime95 at some point to check

EXTRA UPDATE:

Got the FSB to 285Mhz and the RAM to 266Mhz. Running like a little, beautiful beast