• Welcome to TechPowerUp Forums, Guest! Please check out our forum guidelines for info related to our community.

FSB, memory bus, and 1:1 ratio

M

mist303

New Member
Joined
Apr 8, 2015
Messages
13 (0.00/day)
Hello all,

I recently became interested in overclocking my CPU. I had a 12:10 (or 6:5) Memory to FSB ratio which I am trying to mend to 1:1. Thing is, trying to increase the clock rate from the BIOS results in increasing the memory bus in the same ratio. In other words, I had a 333.3MHz FSB and 400MHz MemBus; once I increased the FSB to 400, the memBus increased to 480.

Is there a way I can reach 1:1 ratio?

Also, I'm using a Kingston DDR2 at 800MHz (so DDR 400). Is it being dangerously overclocked when the memBus is 480?

I have a Xeon L5420 currently running at 2.8GHz (reduced multiplier to 7 instead of 7.5 to increase the FSB safely)

One last question, my motherboard's max Northbridge speed is 1600 (OC), which I am currently at (400MHz * 4). Am I overloading it?

34zef88.png
 
400MHz is 1600MHz quad pumped, so it's ok. You should be able to get the CPU fsb to 1600. Give us mobo model please. At work now so can't look at this in detail at the moment.
 
Well, it seems that if you increase your multiplier, you can get closer to that 1:1 ratio without increasing the NB FSB anymore. What is the CPU?
 

:ohwell: Wow. I read that post 4 times looking for the CPU and didn't see it.

I still maintain that increasing the CPU multiplier will raise the CPU speed without raising the RAM speed anymore, bringing the ratio closer. Beyond that, if that chip can't go beyond 7.5, then the only way he will reach that ratio is going slower on the RAM with his current setup.
 
Its that age old Problem

"" Cannot See the wood because the tree's are in the way "" :)
 
Some old motherboards you can find the FSB ratio is tied to the memory and there is a setting in the BIOS to enable or disable this. More details on the model might help.
 
Caring1 said:
Some old motherboards you can find the FSB ratio is tied to the memory and there is a setting in the BIOS to enable or disable this. More details on the model might help.
Click to expand...

It's a Gigabyte EP43-UD3L.

NOTE: That BIOS should give you a system memory multiplier. What is yours set at?
 
Last edited:
rtwjunkie said:
It's a Gigabyte EP43-UD3L
Click to expand...
Yeah, those trees got in the way again. :D
On the main BIOS screen, press and hold Ctrl and F1 to access the Gigabyte M.I.T. screen for more options.
 
Caring1 said:
Yeah, those trees got in the way again. :D
On the main BIOS screen, press and hold Ctrl and F1 to access the Gigabyte M.I.T. screen for more options.
Click to expand...

The current multiplier is 7 instead of 7.5, I can only set the FSB and multiplier using the BIOS (MIT).
I looked around and I can't seem to find the option to disable the link between the FSB and the memory.
 
mist303 said:
The current multiplier is 7 instead of 7.5, I can only set the FSB and multiplier using the BIOS (MIT).
I looked around and I can't seem to find the option to disable the link between the FSB and the memory.
Click to expand...

On that motherboard it's always going to be linked. That's why you need to lower the memory multiplier or ration in the BIOS. That way, when you raise your CPU core speed you don't take the memory/NB beyond what it can handle. Yes, you'll have slower RAM, but without a faster cpu capable of a higher cpu multiplier, that's what you'll be stuck with.

@dorsetknob There's no problem if he has done the sticker mod (or a previous board/cpu owner.)
 
rtwjunkie said:
It's a Gigabyte EP43-UD3L.

NOTE: That BIOS should give you a system memory multiplier. What is yours set at?
Click to expand...

It's at 7 currently (was at 7.5 but I reduced to to increase the FSB safely)

You also mentioned that increasing the multiplier will get me to the 1:1 ratio. I can only have the following numbers: 6, 7, and 7.5 . Also, can you please elaborate on how will increasing the overall CPU clock rate will increase the ratio? I thought it was strictly the bus that controls these things.
 

Attachments

  • asdasd.png
    asdasd.png
    107 KB · Views: 632
mist303 said:
It's at 7 currently (was at 7.5 but I reduced to to increase the FSB safely)

You also mentioned that increasing the multiplier will get me to the 1:1 ratio. I can only have the following numbers: 6, 7, and 7.5 . Also, can you please elaborate on how will increasing the overall CPU clock rate will increase the ratio? I thought it was strictly the bus that controls these things.
Click to expand...

Increase the CPU multiplier, while changing the ratio on the Ram speed so you don't speed your RAM into oblivion. We need to know the current memory multiplier.
 
rtwjunkie said:
On that motherboard it's always going to be linked. That's why you need to lower the memory multiplier or ration in the BIOS. That way, when you raise your CPU core speed you don't take the memory/NB beyond what it can handle. Yes, you'll have slower RAM, but without a faster cpu capable of a higher cpu multiplier, that's what you'll be stuck with.

@dorsetknob There's no problem if he has done the sticker mod (or a previous board/cpu owner.)
Click to expand...

So slower RAM but faster CPU. Is this good for gaming? I mean, shouldn't I be aiming at faster clocks all around?
 
mist303 said:
So slower RAM but faster CPU. Is this good for gaming? I mean, shouldn't I be aiming at faster clocks all around?
Click to expand...

Initially, your RAM will be slower, if you change the strap to 266 or 333. This allows you to overclock the CPU first. On Skt 775 (yes, 771 follows the same rules), always do the CPU first. As you raise its speed, the RAM speed will increase too eventually hitting 400 (or 800MHz effective).
 
Last edited:
opps deleted my post which I thought was a double up... nG!

Anyway, you need to go for the 400 fsb strap. Then adjust ram down to 1:1, which will mean u get back to 800mhz for the ram.

You may need to bump the core voltage a little, but pretty much any chip from that era did 3ghz fairly easily, often without a change from the VID.
 
Turns out my memory speed was being controlled by the motherboard. I fixed it to 400 with a multiplier of 2 (called 2.00D in my motherboard) to make it reach 800MHz. I let my motherboard control the voltages (it raises and lowers them dynamically and on demand which is pretty nice).
I still have the multiplier on 7 tho. I need to test the stability and heat dissipation in my system before going for the final clock rate.
Here's an image of my specs so far:

2w7r08w.png


Thanks everyone!! I will update this post once I get it to 3GHz!
:peace:
 
mist303 said:
Lol, I modded my motherboard :D. It works pretty well too. You can google the mod as it is widely used now.
Here's proof that I'm really using this setup ( just in case :p )
Click to expand...

googled it as you recomended

Now i want a xeon 54xx series Cpu preferably X5470 or X5460 with the mod it would go well in my asus P5q pro turbo motherboard ( to replace the q6600 ) :)

have to start lurking on the buy/sell/trade thread
 
dorsetknob said:
googled it as you recomended

Now i want a xeon 54xx series Cpu preferably X5470 or X5460 with the mod it would go well in my asus P5q pro turbo motherboard ( to replace the q6600 ) :)

have to start lurking on the buy/sell/trade thread
Click to expand...

good luck! make sure you have full compatibility ;)
 
Its a p45 chipset and fsb will go to 1600 so it should be compatable
 
mist303 said:
Lol, I modded my motherboard :D. It works pretty well too. You can google the mod as it is widely used now.
Here's proof that I'm really using this setup ( just in case :p )
Click to expand...
So you can use a socket 771 CPU in a socket 775 mobo with a little mod? <incredulous look> Ok, but it's the first time I've heard of it!

I think there lies the answer to your problem though. That mobo and CPU aren't made to work with each other, so even though you can coax them into working together, it doesn't surprise me that some things aren't going to be quite right, therefore this FSB ratio glitch would be a prime candidate for such a glitch. :ohwell:
 
You must log in or register to reply here.
Back
Top