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read the a64 101, still a bit confused...

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arnoldma

Member
Joined
Apr 4, 2003
Location
Essex, UK
Hi, i've just read some of the a64 101 sticky, but im still a bit confused, so far i got:

there is no NB, thus no FSB, so to overclock u use the hypertransport and the multiplier...

and with the hypertransport there is also a LDT multiplier? and the hypertransport * the LDT multiplier gives the final "FSB" even though there is no FSB... ok, i think what i just said is wrong!!! im so confused...

also i dont get how to over clock ram speeds? and how to get to the final extrenal clock speed!!!

damn y cant thye keep to the good ol'way :cry: :cry: :cry:

plz explain! thanks you!!!!!!
 
It's sort of unclear to all of us exactly what all those acronyms are supposed to mean in the most concrete terms. You've got an HTT, which is about as close as you can get to an FSB. The HTT x CPU multiplier gives you your CPU speed, just like the FSB x CPU multiplier gives you your CPU speed on an AthlonXP.

Now what makes it a little complicated is how its effective HyperTransport bandwidth is derived. The HTT is multiplied by an LDT multiplier, which is then effectively doubled, as its DDR. The HyperTransport bus = HTT x LDT multiplier, and is a bus independent of the CPU and memory buses. The PCI/AGP buses work through this, so conceptually, the HyperTransport is analogous to the FSB, even though it acts nothing like it.

So what you said is actually right.

Ram speeds are derived off of CPU speeds using CPU/memory dividers. Best way to think of them is as multipliers in reverse. With AXP's, the FSBx multiplier = CPU speed. With the A64, CPU speed / memory divider= memory speed. Memory dividers are determined in the weird way that I outlined.
 
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ok, so the HTT would be something like 200mhz and then lets say there was a 10 multiplier, so the total cpu speed would be 2.0ghz?

and then there is a thing called hypertransport bus, which has nothing to do with the final speed of the cpu? hypertransport bus = HTT x LDT

as for the ram, so lets say the cpu speed was 2000mhz (2ghz) and the ram multiplier was 10 then the ram fsb would be 200mhz? i.e. 400mhz ddr?

let me know if anything i said is wrong... thanks a lot for explaining this!!!
 
bump, i would like to get this clear, could some1 please see if what i said is right?

cheers!
 
hmmm, so the hypertransport has nothing to do with the CPU? it just control over things like PCI/AGP? surely when you overclock the HTT wouldn't u be overclocking the PCI/AGP too?
 
on nf3 250 and the KT880Pro or whatever the via chipset is called, the AGP and PCI buses are locked. Now when you change the HTT speed, the HT speed changes as well, as it is directly influenced by the HTT speed. (HTT x LDT multiplier = HT)
 
arnoldma said:
hmmm, so the hypertransport has nothing to do with the CPU? it just control over things like PCI/AGP? surely when you overclock the HTT wouldn't u be overclocking the PCI/AGP too?


well on *some* NF3 mobo's(mostly the NF3-150's) the PCI is not locked, and when you increase the HTT, it also increases the PCI. on most NF3(even the 150's) the AGP is locked at 66, unless you increase it in bios.

and on VIA K8T800( NON-PRO) both the agp, and the pci, on a ratio with the HTT, and both are increased, as the HTT is increased....

Most NF3-250's, and Via K8T800-PRO's are both agp, and pci locked:D

-Jess-

EDIT: you beat me to the post-em button the coolest :sn:
 
In A64, there are these buses external to the CPU:
- the HyperTransport (HT) bus,
- an independent memory bus,
- AGP/PCI bus which can be locked.

In A64, FSB becomes an internal CPU frequency/setting, also called HTT, used to set up CPU clock frequency, HT bus frequency, memory bus frequency.

These posts describe how to set these buses up, as well as the CPU clock frequency using HTT, CPU multiplier, LDT multiplier, memory_FSB_ratio and in turn the memory to CPU frequency locking ratio (or memory divider), ....

Overclocking setting for various bus frequencies (post 8)

Relationship between CPU_memory_divider and CPU_multiplier, memory_FSB_ratio
How to determine memory bus frequency
 
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