bios setup q: how to get DDR 333 RAM to go at 333mhz?

[cjard]

Hi guys, im wondering if someone can advise me on something:

The motherboard manual says "supports up to 333mhz fsb" and it says elsewhere "supports 333mhz amd k7 processor"

In th CPU PnP BIOS setup, is a screen that looks like this:

CPU Type: AMD K7 (greyed out)
CPU Frequency: (choice 100/133/166)
CPU Overclocking Frequency: (adds up to +32MHz to the cpu frequency)
CPU/DRAM Frequency Ratio: (choices are many, 9:13, 4:5 3:4 2:3 1:2 2:1 3:2 5:7 blah..)
DRAM Frequency (greyed out, calculated from CPU * ratio)
CPU Ratio: Locked (greyed out)


now, im confused.. if this mobo does 333mhz fsb, why does the cpu frequency only have choices for 100/133/166?
i note that 333 is twice 166, so if i set 166 CPU frequency then 1:2 cpuram ratio, i see that the ram frequency is 333, but the system will not boot with this.. it doesnt even post.

at the moment the highest i have got the dram to before it wont boot is 224 mhz, on a 3:4 ratio from 166 (on the cpu)

is there something i am missing or not understanding?

 

[Rhagz]

Effective RAM speed is double theclock speed. It is a misleading advertising gimmick used by chip manufacturers. 166FSB x 2 = 333 effective FSB. This is at a 1:1 mem divider though. If you are at 5:4 or something, then FSB needs to be raised. Just use math and match your FSB x divider to equal 333 or so.

 

[Peter]

You fell for the marketing trap - these folks think that 166 MHz DDR equals 333 MHz. It does not. If your PC2700 RAM is running at 166 MHz, then it's doing exactly what it's supposed to do. Same for the CPU side of the business - Athlons run 100 to 200 MHz DDR, often advertized as "FSB200 to FSB400".

 

[cjard]

fortunately, i am not paying for this sytem.. its jsut a work's machine...

so on that BIOS window i should set my CPU frequency to 166 (as that is the highest that it will go) then adjust the cpuram ratio until the machine wont boot any more? that's what i currently have.. and the ram is running at a clock speed of 224 mhz apparently.

am i to understand then, that this ram is misleadingly stamped with 333, and is actually supposed to run at 166mhz.. hence the 224 mhz i have gotten it to run at is as good as i will get?

 

[cjard]

Originally posted by: Rhagz
FSB x divider to equal 333 or so.

if i do that.. set CPU Freq to 166, then ratio 1:2 (making ram at 332) the machine wont POST test.. nothing.. only clear CMOS gets it working again..

 

[Rhagz]

No, leave the RAM at 166. That is what it should be. the effective speed is double the RAM frequency. Thats' ye olde marketing. 166Mhz RAM = 333Mhz marketed RAM. You may get some overclocking out of it, but running 333ram at 448 or whatever you have is probably not healthy for it.

Leave the divider at 1:1 as well.

Edit: Summary would be to set the CPU frequency to 166Mhz, set the divider at 1:1. Clock speeds are double in the FSB, so you would then have your CPU and RAM running at an effective 333MHz, which is what they are both designed to do.

 

[Rhagz]

And if it is just a work machine and you aren't worried about overclocking, then don't bother. You could try stepping up the CPU frequency a few Mhz, this would overclock both the CPU and RAM at the same rate, if you leave the divider at 1:1. I don't know what processor model and RAM you are using, but if it isn't some top-end stuff, then OC'ing won't go very far.

 

[Concillian]

PC2700 = 166MHz DDR the "effective" speed is 333 MHz.

You should be at 166 MHz 1:1

The fact that you can run it at 224 MHz is pretty impressive, though I doubt it's totally stable there. it is VERY rare to find RAM That will run at PC4800 speed (300 MHz or DDR600), so it is not surprising that your computer won't boot when you set the memory to 1:2.

 

[imported_Harbinger]

Originally posted by: cjard
fortunately, i am not paying for this sytem.. its jsut a work's machine...

so on that BIOS window i should set my CPU frequency to 166 (as that is the highest that it will go) then adjust the cpuram ratio until the machine wont boot any more? that's what i currently have.. and the ram is running at a clock speed of 224 mhz apparently.

am i to understand then, that this ram is misleadingly stamped with 333, and is actually supposed to run at 166mhz.. hence the 224 mhz i have gotten it to run at is as good as i will get?

Why do you really care about a pc you dont own ?

 

[cjard]

Originally posted by: Harbinger



Why do you really care about a pc you dont own ?

'cause I have to work on it.. i've been putting up with an ath900, 512 meg pc100, 5400 rpm hard disk since i joined the company.. now i know that 512 megs of any memory will help.. but there are certain operations i need done faster, so i marched down to the geeks area, and pulled out their oldest, non-selling motherboard (which was quite a respectable thing by the looks of it), fittest the fastest processor they had, and 512 megs of some quicker ram..

as you can tell, its been a while since i built a PC, and i've gotten somewhat out of touch with what all the mhz speeds are these days.. the last pc i built was based on an abit bh6, back in the day when the board would go to 133, but pc133 ram just didnt exist..

ah, for the simple life...

so, thanks for the infos guys. i shall make a few changes to the machine setup and run some benchmarks (i.e. if i can print the company product user guide in any less than half an hour, it's worked).

matt