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Lil Help Please?

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Klutch

Registered
Joined
Apr 10, 2004
Wasnt sure whether to put this here or in RAM section, but I figured it was an AMD related problem so...

Hey, my friend is hoping to upgrade his gfx card, but first I asked him for a rundown of his system spec... part of which being the RAM speed.

He sent me this screenshot:

Here

Now, to me this looks like he has 3 sticks of PC3200 and 1 stick of PC2700, but their actually running at PC2100 speed? Am I correct? Does this mean his BIOS is using a memdivider, that we can change to get it running at PC2700?

Ok, now onto the CPU... he has an Athlon XP 2800+.

Since he has an FSB of 166mhz, how on earth do we get his RAM to run at DDR400 (assuming he buys a replacement PC3200 stick for that PC2700)? Would we need to change his FSB and mulitplier to get it so he is running 200mhz FSB? I dont know much at all about Athlon XP's so I'm stumped here?! I checked his motherboard (Gigabyte GA-7N400-L) and it shows DDR400, so it must be possible?

Thats all for now, thanks in advance for any help/suggestions!
 
The RAM is being underclocked from 166 to 133 because of that 12.5 CPU multiplier he's using. Stay away from the "half" multipliers if you want your RAM to run at whatever dividers you set them at.

As for the mismatched RAM, yeah its pretty mismatched. You have 3 different types of RAM in there. I'd say spring for a new 512x2 matched set, that way you could also run proper timings and 1T command rate (not sure if that board supports 1T though please get a second on this).

To run it at DDR400 (PC3200) set the FSB to 200, and use a different CPU multiplier to keep the CPU running at the desired clock rate (stay away from those .5 multipliers!).
 
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As long as all your mem sticks are pc3200, you should run your fsb at 200. Your multiplier shouldn't be locked, at least not downward, so put your multi at 10x and your fsb at 200, and off you go. Your chip will do this with stock cooling and stock voltage. If you want, you can start uppin the multiplier as well, but anything over 11x will start to need more cooling or voltage (probably both).

As you see in my sig, I run my 2500+ Barton at 200x12, but its running at a higher voltage then stock, and with better cooling. Your chip should be able to do the same (although I am not sure if yours is a mobile).
 
Cheers, big help.

Think I've got it right in my head now =) Many thanks.
 
Wait, for Socket A, do not use any dividers, it'll hurt the performance. Run it 100% 1:1 insync.

RAM sticks will run at the speed of the weakest link at default. So if there's a PC2700 RAM in there, they will all default to PC2700 speeds.

MHz Frequency = multiplier x FSB

locked 12.5 x FSB in your case.


Lets' say he overclocks it to 2200 MHz.

12.5 x 176 = 2200

100% in sync, the PC2700 RAM would overclock to 176 and PC3200 RAM would underclock to 176.

PC2700 default is 166 FSB
PC3200 default is 200 FSB


Of course he may need to increase Vcore voltage and Vdimm RAM voltage to hit 2200 MHz, but with good cooling that shouldn't be a problem.
 
Bah this doesnt sound too good.

His multiplier seems to be locked as you say, or atleast he cant find anywhere to change it. But atm he has PC2700 as the weakest link, but its running at PC2100 (DDR133), no? That's what Everest and CPUZ seem to be saying. If this is because of the half (0.5) on the multiplier, then surely we're screwed, cause we cant change it?

Would replacing that PC2700 stick with a 3200 stick solve it do you think? Or is this a case of getting a new motherboard if he wants to run at PC3200 speeds? Maybe even a new socket type if the multiplier is locked on all Socket A's?
 
MHz Frequency = multiplier x FSB, you know that, right?

So he has a 2800+ Barton which is a
12.5 x 166.66 FSB = 2083 MHz part, you know that, right?


With his 12.5 multiplier locked, overclocking can be done by increasing the FSB from 166 FSB upward.

If you increased it to 200 FSB, that would mean 12.5 x 200 = 2500 MHz, and his CPU may not be able to do that.


So it doesn't matter what RAM you have, he's looking at increasing the FSB from 166 FSB to maybe 180-something FSB. He would still need to increase voltage.

So now just make sure in BIOS he's running his RAM at 100% insync, and lower set the FSB to 166 FSB, then overclock up from there, but probably don't expect 200 FSB from this CPU on his system.
 
Of course "the thing to do" if he has no money for Socket 939 is to sell the CPU and motherboard and buy a Socket 754 motherboard and Sempron64.

That sell & swicth would give him the best system in the end and he would hardly have to spend any $ to do it.
 
Yeah I know all about the FSB x Multiplier n stuff, I've got my A64 3200 @ 2.5ghz.

The problem though is his RAM speed. It's running at PC2100 (133), where it should be running at PC2700 (166) like the CPU FSB. If you look at the screenshot you can see. CPU FSB is 166 but memory bus is only 133 (should be 166).

I need to know why it's at 133 instead of 166?

I havent asked him if he saw a memdivider while he was in the BIOS, maybe thats the next step?
 
All right. Of course, the first thing to do is to make sure BIOS options are set for 100% insync 1:1 operation.

Next thing would be to test sticks one by one.
 
Ahhh. Sorted.

It was running at a 5:4 divider (80%).

So the memory is now running at the proper speed of 166mhz (PC2700).

Thanks for all the help y'all.

I still dont understand though, will he be able to run PC3200 memory without overclocking his CPU? 'Cause now the memory is running at 100% of the FSB, so surely that means a max memory frequency restricted by the FSB speed?

Still, PC2700 is a nice jump up from PC2100 =)
 
The CPU was not made for PC3200 RAM but for PC2700 RAM

PC2700 default is 166 FSB
PC3200 default is 200 FSB

He has a 2800+ Barton which is a
12.5 x 166.66 FSB = 2083 MHz part



So in order to run at 200 FSB, he would need to lower the multiplier, but since his multiplier is locked, running at 200 FSB may not be an option.


FSB x multiplier


If multiplier is locked at 12.5


You can't just set the FSB to 200.

Yes the RAM can do 200 FSB but the CPU may not be able to because CPU MHz frequency is FSB x multiplier. And this particular CPU has a locked multiplier of 12.5.


2500+ on the other hand has a locked multiplier of 11.

11 x 200 = 2200 MHz

Now if he had a 2500+, then maybe he could do 200 FSB because

11 x 200 = 2200 MHz
but
12.5 x 200 = 2500 MHz


and desktop Barton core is more likely to be able to do 2200 MHz than 2500 MHz.
 
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