Memory Divider for ASUS P4C800-E

craigcharlie

Hi all,

I just bought a ASUS P4C800-E but I'm currently not able to afford the pc3200 RAM that goes with the motherboard. So I'm running the pc2100 RAM from my old motherboard, but I want to make sure I'm not causing a bottleneck for the processor. So I believe I need to set a memory divider?

However, I can's see how to set a memory divider in the bios that comes with this ASUS board. I've attached the screenshot from the bios that would seem to relate to this.

What I'm thinking is that you can just independently set the speed of the RAM for this board... since all the settings are "auto" is a memory divider being applied automatically?

If this is the case, that brings up an interesting question...if I decide to go the overclocking route and get pc4200 or higher, then how can I ensure the speed of the ram will match the speed of the processor, given that the only speed options listed for ram in the bios are 266mhz, 333mhz, 400mhz, and auto? i.e. will the auto setting result in the RAM matching the bus speed of the processor, or will it just autonegotiate down to the highest listed setting - 400mhz?

Let me know if this doesn't make sense!

cheers,
C

craigcharlie

hiya, sorry for bumping this, but I thought if it were on the first page then maybe someone might see it tonight.... was hoping to try overclocking a bit tonight

SouperComputer

with PC2100 you ARE causing a bottleneck for the processor. But you can still overclock until you get faster RAM.

You can use the divider to keep the RAM within spec (ie 266Mhz) while upping the FSB. You will need adjust the divider to keep the RAM below 280Mhz or so. That way you can be sure that any instability caused is from your CPU overclock. You may even need to go below 266 if a certain FSB is being used!

This will let you see what you can clock your CPU to. Of course, in terms of the processing power it actually has, it will be limited until you get faster RAM.

From what I gather (not 100% sure and im pretty sleepy right now!) the Auto option in your BIOS is to run the RAM @ the SPD (Ie RAM maker's) speed, in relation to the FSB.

craigcharlie

thanks for the info souper! tired as I am, I'm gonna try it right now for a minute and see how the OC goes!

craigcharlie

awesome, worked great, thanks!

currently overclocked from 3.2 to 3.5 without even raising vcore (don't want to raise wattage yet since I only have stock heatsink, currently idling at 50c)

I see what you mean about the memory, it's now showing as 146mhz....I assumed that if you set it to 133 that it stayed 133...thanks for clearing that up!

Thanks for your help! I'm tired now, I'll try for more tomorrow!

cheers,
C

unkel

First, download your mobo's manual from ASUS - I just did for you

Normally the multiplier is locked on the S478 Northwood. In your screenshot it shows 18, so it looks like you might be the owner of a very special unlocked one

Can you set the multi to 24? If so, at least your cpu is running at full speed

SouperComputer

First, download your mobo's manual from ASUS - I just did for you

Now thats commitment!


What cooler are you using Craig? Depending on what it is, id consider changing it before pusing the Vcore up.

craigcharlie

thanks for looking guys!

Unkel - the screenshot is actually from the manual, not from my computer cheers for looking at the manual! Not in front of the pc now but I think the multiplier is 16.

souper - I'm getting a different cooler tomorrow, a nice zalman.

I'm waiting to do further overclocking after that... though tbh, based on what souper said about the fsb pushing up the ram speed as well, I don't think there's much point til I replace my 2100 ram. That's the next step!

cheers guys!

Charlie

SouperComputer

I'm waiting to do further overclocking after that... though tbh, based on what souper said about the fsb pushing up the ram speed as well, I don't think there's much point til I replace my 2100 ram. That's the next step!

You can use the divider top prevent your RAM overclocking. IE 2/1 divder means 100/50 (FSB\RAM Speed) if you follow me. In this case you have a quadpumped FSB @ 400mhz and DDR RAM running @ 100Mhz.

See what you get out of the chip and then grab some good RAM.

You should be able to get to 3.8 anyway, make sure you use good thermal paste (arctic silver5) and have good case ventilation.

VeVeX

See - http://forums.extremeoverclocking.com/showthread.php?t=108657

Should cover any questions you may have.

Id recommend getting some pc4000 memory or good pc3200 ie GeIL one.

craigcharlie

hmm, then I'm still a little puzzled. if you take a look at my screenshot, you'll see that the only 2 things I can change are the frequency of the fsb and the frequency of the memory.... I can't change the 'cpu ratio' since it's a p4 northwood.

(well actually I can also change agp pci frequency... might have to adjust that downward so my old 4x agp doesn't give up the ghost)

so I thought that the dividers for ram were set as follows:

200 is 1:1
166 is 5:4
133 is 3:2

such that overclocking my FSB to 230 mhz, and setting the Ram frequency to 266mhz, meant that my ram would be running at 306 DDR (or in other words, 153 mhz "real" speed instead of the 133 mhz.)

ok never mind.... I've just gotten vedex's message and it's PURRRFECT!!!! thanks dude, that details every setting and what it means, I couldn't ask for a better guide.

the guide vedex posted confirms what I was saying about the ram, so I do understand what's going on.

cheers for everyone's help!
Charlie