FSB question

[yy3d]

A64 can run with 1G FSB speed. Is it better to use ddr 500 memory? does those those amd socket 939 mainboard only support up to ddr 400 memory? If i use ddr 400, the sys 'd stay in 400 FSB right? is it possible to make it oc to 500 fsb to fit to cpu's 1G fsb?

 

[Losty]

I'm not sure what you are asking, but I do believe the boards used, these days, do have a bandwidth of 1000mhz. The memory used is usually ddr 400(running 200x2). Most oc'ers increase the HTT of the board since the chips are locked upwards. The memory settings are separate (they now use dividers so you can keep your memory at 200 while oc'ing the HTT)

For example: A64 2800+ Multiplier 9 @ 1.8ghz stock you can oc by:
Multiplier 8x
HTT = 297
Memory divider 133 ( 133/200 = .665 ... so 0.665x297 ~ 198)

HTTxFID is like FSBxMultiplier
so cpu speed = 2384 ~ 2.4
HT (i believe this is what you are saying - 1ghz) = 3x297 ~ 900


You could also by higher clocked memory instead of ddr400 and oc your system without a divider or just oc high end memory

Not sure if i'm explaining this 100%

Hope you got an answer.

 

[Mogadon]

This article was posted in a recent thread, you may find it useful.

 

[tyborg]

basically, it's best to overclock with no divider, as your RAM will run faster. But if your RAM can't take it, then you have to use a divider to stay stable. with DDR500 RAM you basically pay for a garuntee that you can overclock to a fsb of at least 250 before needing to use a divider. As long as it's not DDR2. DDR2 is not compatible with DDR1 motherboards. remember that the FSBx2 gets your DDR speed since DDR is double data rate. As far as the 1GHz, that comes from the HTTLink (Hyper Transport link) you get that from the FSBxHTTLink. If the FSB is 200 and the HTTlink is at 5x, your total HT FSB is 1Ghz. I think for NF4 boards, 1ghz is the maximum stable unless you increase the northbridge voltage, which the performance gains are hardly worth the risk. Crossfire boards supposedly can go beyond 1GHZ without breaking a sweat.

 

[theMan]

you are confusing terms. a64's do not have an FSB. it has Hypertransport (which runs a 1ghz) and HTT (wich runs at 200mhz) the memory speed runs with the HTT, so the memory runs at 200mhz, or DDR400. now, if you overclock, in which you increase the HTT, then the memory speed increases, so getting DDR500 may be useful.

 

[klocwerk]

Tyborg, most NF4 mobos can run the HTT faster than 1ghz, that's just the stock speed. Like anything else, you can OC it.
I got mine up to 1250 stable when isolated from CPU/mem in testing.

 

[theMan]

yes, but the correct term is HT, not HTT. interchanging them just confusing people.

 

[Sumotku]

What's the worst that can happen from running an HTT at say 10--15 percent over the rated 1000??

 

[klocwerk]

Originally posted by: Sumotku

What's the worst that can happen from running an HTT at say 10--15 percent over the rated 1000??

As I was corrected above, it's the HT, not HTT. heh.

Absolute worst is that you fry your motherboard.
To avoid that, take it up slowly. Once you hit a point where the system isn't stable or won't boot, clear the BIOS and back it off a bit. You won't kill your mobo that way. It'll fail to boot long before it'll kill itself.

As I stated above, I got mine up to 125% of it's rated speed.

 

[Sumotku]

In my very first O.C. attempt I pushed cpu frequency on my new Opty 175 as far as 270 x10 and backed it off content with 240 for 23/7 use (gotta sleep sometime... ) and in the HTT/HT confusion didn't make the connection that it was the 1-5x setting in bios, so was running the HT (see, I'm learning) at 1200. It was stable, but I ran that way for two days under lots of testing and working. I hope I didn't prematurely jackulate it. Also, I didn't apply a mulitplier to the OCZ ram so it was tapping out a wicked morse code at 480 MHz. There, I feel better. Open to advice, btw.