Overclocking AMD 64 Help

[PizzatheHut06]

I've been trying to understand overclocking on an AMD 64, and is so much more complicated than Athlon XP's. I've been doing some searching on Google, but am still confused about the relationships between LDT, memory dividers, HTT multiplier, etc. Does anyone have a link to a good, instructive guide on overclocking AMD 64's?

 

[Nubius]

Assuming your board is 2000HTT it goes like this:

CPU HTT in the BIOS is 200, that's kind of like the FSB on an XP, except of course in your case with the 2500+ you'd see 166 because of it being a 333FSB chip...

Anywho on AMD64's is 2000, and some are 1600, but we're going to focus on 2000 for right now.

CPU HTT = 200

the LDT multi or sometimes seen as Link speed multiplier for a 2000HTT board will be 5x

200x5= 1000, and it being 64bit is 1000x2 = 2000

You DO NOT want the total going above 2000, unlike socket A boards where you'd gain performance from OC'ing the FSB this is not the case.

So assume you OC'd your 64 to 250 HTT, You'd need to lower your LDT (link speed multi) to 4x so

250x4 = 1000 x 2 = 2000 .....still 200 see? if you go well above 250 then you'd have to make it even lower to like 3x.

Memory divider is exactly what it says.....your CPU if given a good one and good mobo can hit like 300HTT+ which not all RAM would hit, so you'd need to then use a divider to keep the RAM running at like 250 or something lower than 300 while your CPU is infact still running at that higher HTT.

That's about it

 

[PizzatheHut06]

Thanks dude, I understand the HTT multiplier business, but where does that fit in with the overall speed of the chip itself? Is there a separate multiplier for the CPU frequency?

 

[Nubius]

but where does that fit in with the overall speed of the chip itself?

I just explained that.....the 2000HTT overall motherboard bus is determined by that multiplier which is 5x if it's 2000htt and 4x if it's 1600HTT

With that information in hand you can conclude that there will be a 2nd multiplier...one for the system bus, one for the CPU

 

[PizzatheHut06]

Ok thanks.

 

[Wayniac]

You can keep the RAM running at a lower speed also with the RAM:CPU-FSB ratio (it is called something like that). You'll notice when you look at your setting to adjust your RAM, that you have a MaxMemclock. It will probably be at 200. By lowering this, it'll let your RAM run at a lower speed based on the FSB while the processor runs at a higher speed using the FSB and the multiplier. The ratios are as follows:
200 = 1:1
166 = 5:6
133 = 2:3
100 = 1:2

This is what I understood it to be anyway, and ever since I've been experimenting with overclocking, I've had no problems.

 

[Nubius]

That's the memory divider, which is also something I explained above.

Of course if you have good RAM it can follow up the CPU quite high 1:1