A8N-VM CSM & Opt 146 CABYE

rolandrat

rolandrat

rolandrat

Associate
Joined
11 Jan 2005
Posts
192
Right then, i understand that these optys are good on the overclocking front.
Can someone explain to me in very simple terms, with pictures and crayon drawings, what the hell I need to change in the bios to ramp this baby up a bit, because from what i can see the multiplier is fixed on this bios.
Am I right, or am I missing something.
Thanks in advance.
RR
 
You are right - the multi is fixed.

To increase the speed of the CPU you have to speed up the HTT.

The multi in that chip is 10x, and the default HTT is 200MHz, so your basic speed is 2GHz. If you increase the HTT, to say 250MHz, then your CPU speed will be increased to 2.5GHz.

Be aware that there are several side effects to increasiong HTT speed.
- Hypertransport (HT) speed is derived from HTT with another multi, defaulting to 5x
- DDR speed is derived from HTT

HT speed is 1GHz (200 x 5), so when overclocking you need to set this to 4x for up to 250MHz HTT, and beyond 250MHz, set it to 3x. You have to keep HT at or below 1GHz for stability.

DDR speed will probably be an issue as well - most people will have PC3200 DDR, which is rated at 200MHz. Generally you will have some headroom in this, but unless you have faster memory it's wise to implement a divider on the memory to stop it from being overclocked too much. A 166MHz (DDR333) divider should suffice up to 250MHz, and a 133MHz (DDR266) divider beyond 250.

Something else to bear in mind is that you may have to up the VCore to keep it stable once you start overclocking it.

Hope this helps.

Hav
 
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