So I've read in the sticky "Quick and dirty A64 clocking guide" as well as other forums that you should keep your Hypertransport speed (LDT x HTT) around 1000. But no one ever explains why this is so critical. What's wrong with running it slightly above stock, say 1100?
Why Is It So Important to Keep Hypertransport Around 1000?
- Thread starter marks70
- Start date
On older chipsets going even like 20 over 1000MHz made your system completely unbootable so we got used to staying well under 1000 rather than going over. Recently I've seen mobos do 1150 with no problems but there really isnt any point to going over anyway (hell, there's no point to being over like 600MHz).
Why - what do you mean exactly?
On both my ASUS a8n-sli Premium (the one I had before my current mobo), and my current DFI Lanparty mobo, I've had the hypertransport speed way over stock. I've never once- not once - even had to increase HT voltage to keep them running stable.
Look at my sig - I'm currently running at 288x4. I don't need extra voltage for chipset or HT - just vcore for my CPU. HT speed is stable no matter what I put it at.
I guess if you have a cheap motherboard, you'll have issues - but the two boards I've tried didn't even notice an extra 100 or 200 mhz over stock speed.
If you are stable- leave it cranked up - why not?
That was my point. I've had mine running at 1100Mhz, and it seemed to be totally stable. But due to what I've read about not going over 1000, I back it down to 880Mhz (220x4). On the other hand, I don't see any performance difference between running it at 1100Mhz vs. 880Mhz.
I've never seen anything that shows how HT speed affects performance of anything.. Isn't most of the I/O
taking place at less than 200mhz ?
I've set mine as low as 2x without any change in system performance.
taking place at less than 200mhz ?
I've set mine as low as 2x without any change in system performance.
RichUK
Lifer
- Feb 14, 2005
- 10,341
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The only problem with running a higher frequency on the HT link, is instability caused by a high level of electrical noise through the motherboard tracers.
The tracers are the copper interconnects embedded in the PCB, that provide a data path for the I/O's (Input - Output) of both the chipset and the HT controller on the AMD CPU.
Depending on the quality of the PCB (How many layers it has), and the layout of the tracers, this will denote the boards capability of a frequency higher than 1000Mhz.
the vLDT (HT Voltage) that is used is very low to reduce the effects of electrical noise (aka interference), however, when you increase the operating speed of the HT, more voltage might need to be used to stabilise its operation. But i do agree wit the above comments that a high frequency HyperTransport is not needed, as the bandwidth is just not needed, it would be if you had memory communicating on the HT aswell and needed to compensate for this high use of bandwidth, like the FSB model, but this is not true, as memory on the A64 platform has its on channel in which to communicate. HT is used for the other I/O devices such as AGP/PCI-e, SATA etc
So basically the HyperTransport never gets saturated, with just a single HT link, however, that is different in multiple socket opteron boards which use there HT links to transmit memory data between the different CPU's to share. so this comes in handy in that scenario. But with s939 use there is no benefit, and really no benefit above 600Mhz, i remember a review where they kept reducing the HT frequency until it impeded the system, and i think it was around 400Mhz when there was performance hits from the reduced frequency.
The tracers are the copper interconnects embedded in the PCB, that provide a data path for the I/O's (Input - Output) of both the chipset and the HT controller on the AMD CPU.
Depending on the quality of the PCB (How many layers it has), and the layout of the tracers, this will denote the boards capability of a frequency higher than 1000Mhz.
the vLDT (HT Voltage) that is used is very low to reduce the effects of electrical noise (aka interference), however, when you increase the operating speed of the HT, more voltage might need to be used to stabilise its operation. But i do agree wit the above comments that a high frequency HyperTransport is not needed, as the bandwidth is just not needed, it would be if you had memory communicating on the HT aswell and needed to compensate for this high use of bandwidth, like the FSB model, but this is not true, as memory on the A64 platform has its on channel in which to communicate. HT is used for the other I/O devices such as AGP/PCI-e, SATA etc
So basically the HyperTransport never gets saturated, with just a single HT link, however, that is different in multiple socket opteron boards which use there HT links to transmit memory data between the different CPU's to share. so this comes in handy in that scenario. But with s939 use there is no benefit, and really no benefit above 600Mhz, i remember a review where they kept reducing the HT frequency until it impeded the system, and i think it was around 400Mhz when there was performance hits from the reduced frequency.
rise
Diamond Member
- Dec 13, 2004
- 9,116
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