[REQ] Overclocking - CPU(AMD Phenom II x4 945) + MOBO(ASUS M4A79T Deluxe)

[Dlaw]

At the stock 200 HT Ref., the first frequency is 800, followed by 1066, then 1333, then 1600. The ratios, from low to high, are 4, 5.34, 6.665, and 8. That's why your first divider is showing as 1068, because that's what it is.

So, by my math, an HT Ref clock of 250 will get you ~1333MHz on your ram by using the 1066 divider, and 250*15=3.75GHz. In order to get 1333MHz on the next lowest ram divider, you will need an HT Ref clock of about 333. That's probably higher than your motherboard will support.

Now, your memory may support the 1424MHz that you show as the second option in post 80. The only way you will know is if you try.

 

[trents]

I agree with Dlaw when he says the only way you will know if it will do 1424 is if you try. You seem reluctant to do that. You can calculate frequencies until the cows come home and you won't know until you try.

It would surely require that you over-volt the ram as I mentioned earlier and you could also try relaxing the timings a bit. I would also suggest lowering the CPU multiplier a bit temporarily so that you know any problems with boot will not be caused by the CPU.
speed being too high.

Have you thought about buying some 1600 mhz ram? That would totally eliminate this problem since it would give you headroom above 1333 mhz for the ram. Ram is dirt cheap right now.

 

[I.M.O.G.]

For memory voltage, I wouldn't go beyond 1.7V on air, but many other people do. Even when cold (on the CPU, some cold creeps over to the ram through the motherboard), I rarely go above 1.75V. Your memory stock voltage is 1.5V, so 1.65V is a decent bump. Many memory default at 1.65V. Increasing memory voltage may increase stability if you are trying to run above 1333MHz on your memory. Too much voltage can be as bad as too little.

At the stock 200 HT Ref., the first frequency is 800, followed by 1066, then 1333, then 1600. The ratios, from low to high, are 4, 5.34, 6.665, and 8. That's why your first divider is showing as 1068, because that's what it is.

So, by my math, an HT Ref clock of 250 will get you ~1333MHz on your ram by using the 1066 divider, and 250*15=3.75GHz. In order to get 1333MHz on the next lowest ram divider, you will need an HT Ref clock of about 333. That's probably higher than your motherboard will support.

Now, your memory may support the 1424MHz that you show as the second option in post 80. The only way you will know is if you try.

Thank you dlaw, I get confused with this stuff too - hard not having the bios in front of you.

 

[Dlaw]

I hear ya, IMOG. I actually had all of this figured out on a piece of paper from back when I was getting my overclock strait.

And actually, if you want to get technical, all of those are divided by 2, because the BIOS of his board shows DDR rates, as opposed to the usual rate-per-stick deal. My old ASUS board showed the latter, so for me it was 2, 2.67, 3.3325, and 4, which translate into the usual DRAM ratios.

 

[trents]

I'm glad I'm not the only one that finds memory dividers confusing. Through experience I kind of have a feel for what changing the divider will result in and it just seems easier to me to change it and try it to see how it actually turns out.

 

[I.M.O.G.]

Its easier when you are sitting in front of it. Especially now that many bioses do some of the math for you. Some bioses will show you the default divider setting, and what you end up with you have to calculate. Some bioses will do the math for you, but only based off of whatever FSB you booted at - if you change the FSB while in bios, the math won't be right. Other bioses do the math for you, and even if you change FSB the dividers are still accurate.

Pretty much, the way dividers have been implemented, and the way they are represented in BIOS, has always been a confusing implementation. They could be presented in a way that really simplified things, but they aren't.

 

[Dlaw]

True story. I remember what a pain in the butt it was to figure out Dolk's guide in the memory section, because it was different in my BIOS.