Memory strap??

[Th3-R3as0n]

Can somebody please explain to me the memory ratio's and the Memory strap.. I dont exactly know what they mean..

I Would like to know for future reference and maybe to OC my PC.

What exactly is it.. What should i set it to in my system?

Also does anyone else have the same CPU OC'ed and if you do how much did you get it to..

 

[Th3-R3as0n]

Ok i realize that the Fsb dictates the Memory speed but how do you get the ratio or "divider" to work out the memory speed?

 

[JrRacinFan]

Intel has in basics RAM multipliers, the newer AMD stuff has RAM dividers.

Ok, I will take my setup as an example, at a stock 200fsb(800mhzQDR) I have to run a 1:2 divider/multiplier to be able to have my RAM at its stock of 400mhz (800mhzDDR).

Now if I wanted to acheive the same ram speed but at a 266fsb(1066mhzQDR) I would have to use a 2:3 divider.

As for AMD, whatever your cpu speed is, you would set a divider and that is what your ram speed would be set at. Most common is CPU/7, for example 2.1Ghz with CPU/7 has a RAM effective speed of 300mhz (600mhzDDR).

I hope this helps.

 

[Th3-R3as0n]

Thanks jr it cleared quite a bit up but how did you get 7 for the divider and how would you change that?

 

[JrRacinFan]

For AMD, its strictly all set in bios. Either by choosing cpu/fsb speed and the divider itself, or by choosing the cpu's fsb and the memory's fsb.

Sorry, my knowledge of newer AMD stuff is actually very quite slim, but like I said I know enough about them that I could overclock one if needed.

 

[Wile E]

on AMD chips, cpu speed dictates ram speed. Setting different ram speeds in the BIOS, changes the divider. So, with your 6000+, if you set the ram speed to 800Mhz DDR (or 400MHz real speed, depends on how your bios lists it), the ram speed if derived by dividing the CPU speed by 8. So, 3000/8 = 375Mhz (750Mhz DDR). Check cpu-z, and I'm willing to bet ram speed is read really close to 375MHz.

Now, if you change the cpu multi, the divider will actually change as well. Lets say you leave the fsb at stock (200), but change the multi to 14x. For the 800Mhz setting, the divider will actually change to 7. 2800/7 = 400 (800Mhz DDR).

Now, if you take that same setting, but raise the fsb by 10Mhz, you get 210Mhz*14(the cpu multi)= 2940Mhz So now your ram speed is 2940/7= 420Mhz (840DDR). So now your ram is actually overclocked, but your cpu is underclocked.

It's confusing at first, but starts to make more sense as you play with the settings more.

My suggestion for the begining OCer is to lower the ram speed by 2 options in the BIOS, then start OCing the fsb by 2Mhz at a time.

After you find the max cpu speed, you can try to raise the ram speed.

I got my 6000+ to about 3.4GHz, btw.

 

[JrRacinFan]

OK thanks Wile E, I am unknown to newer AMD stuff. That cleared up a little bit for me too.

 

[Th3-R3as0n]

Ok i see.. But what about the multiplier on the FSB would that affect the speed of the RAM?

Also, in Cpu-Z it says my memory is running at the same speed as my Fsb is this right? i have OCZ 2GB XTC DDR2 800?

 

[boshuter]

Just to add to JR's explanation of dividers... the straps you asked about are fsb speeds programmed into the chipset, they can vary by motherboard manufaturer/model. The straps have different sub timings for the memory so you can clock much higher but with looser timings. Thats why you will see performance take a hit on some boards when you go from 399fsb to 400fsb (it has a strap at 400fsb). Some newer boards allow you to set which strap you want to run on in bios.

You can get around the performance drop if you set you fsb right below the strap in bios, boot the pc then use Clockgen or SetFsb to clock up.

 

[Wile E]

Ok i see.. But what about the multiplier on the FSB would that affect the speed of the RAM?

Also, in Cpu-Z it says my memory is running at the same speed as my Fsb is this right? i have OCZ 2GB XTC DDR2 800?

You have to manually set ram speeds, timings, and voltages in the bios. Many kits boot at a lower speed than they are rated, for compatibility reasons.

And what's this fsb multi you are talking about? I mean, what is it actually called in your BIOS?

 

[Th3-R3as0n]

Thanks e wile and boshunter

@ e wile.. why does the multiplier change from 8 to 7 when the multiplier is lowered?

Edit: sorry its the CPU multiplier.. wrong wording..

 

[Wile E]

Thanks e wile and boshunter

@ e wile.. why does the multiplier change from 8 to 7 when the multiplier is lowered?

Because it's trying to maintain an 800Mhz ram speed, without going over. (That's if you actually have it set at 800MHz in the BIOS). It always assumes a fsb of 200Mhz tho, so if you crank up the fsb, you rasie the cpu speed, and therefore the ram speed.

 

[Th3-R3as0n]

So then if i changed the Ram speed the multiplier would become higher or lower correct?
and in theory it would be better to have a low multilier to have a higer FSB which therefore means i have a faster RAm speed?

The RAM speed in the bios is set to 200 mhz real time..

 

[JrRacinFan]

@boshuter

That is something I forgot to add. Thank you for clearing that up.

 

[Wile E]

So then if i changed the Ram speed the multiplier would become higher or lower correct?

The RAM speed in the bios is set to 200 mhz real time..

Then your ram divider is currently 15. The divider is always a whole number, so sometimes an AMD will run ram lower than what yous set it at, because it tries not to go over on the ram speed. This happens on the ODD numbered multis the most.

With your ram set to 200, you can likely just clock away now. After passing 210fsb or so, I'd say you'll probably want to lower your HT multiplier (Sometimes called LDT instead of HT) to 4X (sometimes listed as 800Mhz)

 

[Th3-R3as0n]

But i want to know how you know that the divider is now 15.. and would a lower CPU multi and a higher FSB mean a faster Ram speed?

Also what is the HT effecting if i change it to 4X?

Sorry for so many questions.. im just inquisitive

 

[Wile E]

But i want to know how you know that the divider is now 15.. and would a lower CPU multi and a higher FSB mean a faster Ram speed?

Also what is the HT effecting if i change it to 4X?

Sorry for so many questions.. im just inquisitive

I know the divider is 15 because I know your CPU speed is 3000Mhz, and I know your ram speed is 200Mhz. 3000/200=15.

The HT is another bus on AMD boards. It's supposed to run at 1000MHz stock. The multi works off of the fsb. So stock is 200*5=1000. Going too far over 1000 can sometimes cause instability. Plus, going over 1000 on it doesn't show any performance gains. So, if you raise fsb to 210fsb, the HT speed would be 1050MHz. If you lower the HT multi to 4, it would run at 810Mhz. Running it at that speed causes no performance loss, but is generally much more stable.

 

[Th3-R3as0n]

Ok i got it now thanks alot wile E cleared everything up for me..

 

[Wile E]

Oh, found a nice little picture that should help you with AMD's mem straps. It does a far better job at explaining it than I could ever dream. lol. I guess a picture really is worth a thousand words, huh? lol.

 

[largon]

Can somebody please explain to me the memory ratio's and the Memory strap.

There is no such thing as "Memory strap" on AMD systems. It's Intel-only.

btw, why are you running RAM rated for DDR-800 at DDR-400?

 

[Th3-R3as0n]

@ largon i dont fully understand what u mean mate..

What is the best memory ratio to have?

 

[Th3-R3as0n]

Well this is what i have so Far.. What you guys think?

3d Mark 06 score is embarrasing

ok.. glitch i cant insert the image or click on anything in the reply bar ????

 

[Th3-R3as0n]

OK i think i got it

 

[Wile E]

Seems a bit low. What catalyst version are you using?

CPU OC seems to be going well tho. For the ram, try setting the voltage to it's highest rated (2.1V I'm guessing), and set the timings to 4-4-4-12 and see if it will run stable like that.


Oh, and Largon was just getting you on a technicality. AMD's don't technically have a mem strap. Mem strap is Intel only, and relates to how the chipset sets it's internal timings and ram speeds/timings and usually works in conjunction with the fsb speed. Tho some boards let you set the strap independent of fsb. In other words, don't worry about it, we knew what you meant. lol.

 

[Th3-R3as0n]

Lol ok thanks.. i will try those timings today.. But the problem is in my bios i get more than just 5 or 6 DRAM timings i get about 15???