ASUS Overclocking - Drops RAM Speed?

daedal · May 2, 2005, 02:00 PM

I recently decided to jump the gun and overclock my PC. I used my motherboard's built-in overclocking option pushing up to a 20% overclock bringing my P4E 3.0Ghz to 3.6Ghz.

I've ran several tests and everything is running smooth as silk. Not a single crash or lockup and running steady under 50c under heavy load and around 36-38c when idle so no problems there.

The thing is, overclocking has brought my RAM speed down to 266mhz (or 233, can't remember). Is this normal? Will it affect my Dual-Channeling and is it really hitting my RAM? I'm just wondering why it would underclock my RAM. I really don't know much about OCing which is why I made sure I had proper cooling before I attempted this but that's pretty much the extent of my knowledge. Any help is appreciated.

Sandok · May 2, 2005, 02:12 PM

Ya it's normal... Don't use the auto settings! Go and set the jumper speeds manually and um, set the ram to 1:1 so it Oc's too! I push 10% not more cuz heat is an issue for me! You seem free of that so go on!

daedal · May 2, 2005, 02:18 PM

So it essentially downclocks the RAM to compensate for the heat?
And I don't know how to set the Jumpers manually. Guess I'll have to find a Tutorial on it from somewhere.

davidnsibs · May 2, 2005, 02:18 PM

this may sound silly, but when you say 233mhz or whatever, isnt that 233mhz = 466mhz DDR (an overclock of 66mhz ddr)

Sandok · May 2, 2005, 02:32 PM

Ya use CPU clock and see... At least with me it'd underclock my ram but just a bit. But if it should normally run at DDR400 and it's not well, then it is slow. And manual is easy mate, just go in the bios, set the manual config and u should see a FSB... Raise it up!

daedal · May 2, 2005, 03:58 PM

Might be overclocked.. I haven't noticed. Hmm. I don't have any cooling units on my RAM though..

*RyderOCZ* · May 2, 2005, 10:13 PM

When you use the AI overclocking it sets a divider 6:5 or 5:4 for the ram to keep it at 200 (what the mobo considers normal)
If you set AI overclocking to "Manual" you should see some new options appear and you can set the FSB and the Ram speed to DDR400 (1:1) That way every 1 MHz FSB will raise the ram speed equally

Hope that helps

daedal · May 3, 2005, 01:42 PM

Thing is I don't want to OC the RAM, just the Processor. Is there a way to do that?

*RyderOCZ* · May 3, 2005, 01:55 PM

Well that is what you have been doing, if you are running a divider (6:5, 5:4, 4:3 etc) then the FSB and CPU are higher but the ram is left at stock, but the ram will underclock if you don't get the FSB to a certain level. Example...230FSB x 5 = 1150 / 6 (6:5 CPU/Dram divider, bios may call it DDR333) = 191 ram speed. 241FSB x 5 = 1205 / 6 = 200.8 ram speed.

Did I explain that ok? or confuse you more?

daedal · May 3, 2005, 05:13 PM

More confused than anything else now.

I think I'm starting to grasp what you mean though.

So it divides the total of FSB x Multiplier by "Y" (dunno where it gets that value from) which end up being the RAM's FSB speed? Is that it, or am I off? Thanks for the help by the way, Ryder. I appreciate your taking the time.

*RyderOCZ* · May 3, 2005, 05:35 PM

Ok...Your motherboard calls the various dividers something different.....you have DDR533, DDR400, DDR320, DDR266..maybe more. When I talk about a Divider, this is the ratio of FSB to DRAM speed, we display it like this 3:4 with FSB listed first so if FSB is runing 3 MHz the ram is running 4 MHz (faster or upclock ratio)...follow?
If we were running a 4:3 divider the FSB would be running 4 MHz and the ram would be running 3 MHz (slower or downclock ratio)

Lets start with DDR400...this is a 1:1 ratio...every MHz that you set the FSB the ram runs exactly the same...so 200FSB 1:1 = 200 Ram speed or DDR400

DDR320 is a 5:4 ratio divider so set FSB to 200 * 4 (the DRAM multiple in our ratio) = 800 then divide by 5 (our FSB multiple) = 160 ram speed or DDR320.

Making sense now?

If you use a divider that is under DDR400 (DDR320, DDR266) your ram will be running slower than your FSB setting....if you use DDR533 your ram will be running faster than your FSB.

Now if you use a divider but overclock the FSB...you can overclock until you get the ram back to 200....so if you set 250FSB and use the DDR320 (or 5:4 ratio) you would have 250 x 4 = 1000 then divide that by 5 = 200 ram speed or DDR400. So now you have your CPU running at 3.75GHz (15 * 250FSB) but the ram is only running 200 like it is rated for

Hope that helps

daedal · May 11, 2005, 09:01 PM

If I try to push it up to 4.0Ghz, the PC doesn't POST. Could it be RAM overheat, or could it be because I simply have "value" RAM? And what would be my RAM speed right now? Runs at 400mhz stock but now I'll all confused..

I know it still runs dual-channel as seen on my POST but apart from that, I'm wondering if my RAM is slower than it used to be.

*RyderOCZ* · May 11, 2005, 09:07 PM

Click the "memory" tab on CPU-z there at the top....it will show the ram timings and the ram speed....like this...see the right hand pic of CPU-z

daedal · May 11, 2005, 09:09 PM

At work right now but I think it was something like 190 and with a FSB/DRAM 3:2 ratio.

*RyderOCZ* · May 11, 2005, 09:24 PM

Well if its running 190 with a FSB of 240 the its not 3:2....are you meaning when you try 4.0GHz?

It may well be that your CPU won't run 4GHz....leave the 3:2 divider set (DDR 266) and slowly push up the FSB and your Vcore on the CPU until you find the max the CPU will go....then you can try to raise the divider and get the ram running faster....follow?

daedal · May 11, 2005, 09:25 PM

Runs at 190mhz 3:2 @ 3.6Ghz
So, if FSB is 190 and the DRAM ratio is 3:2, does that mean

190 x 2 (ratio) = 380 = RAM Speed?

*RyderOCZ* · May 11, 2005, 09:30 PM

You have the 5:4 ratio set....240 FSB speed x 4 = 960 / 5 = 192 ram speed...or DDR384...see how I got that?

daedal · May 11, 2005, 09:44 PM

Aha, now I'm starting to pick it up.

Where did you pick up that I was running a 5:4 ratio though? Just out of knowledge?

*RyderOCZ* · May 11, 2005, 09:45 PM

you said ram speed was 190 while fsb was 240...5:4 is only ratio that resulted in those numbers....3:2 would have been ram at 160

daedal · May 11, 2005, 09:51 PM

Oooh.. crafty.

Thanks for the info!

*RyderOCZ* · May 11, 2005, 09:53 PM

More than welcome

Post here if you have more questions.

Canon20d · May 12, 2005, 08:12 PM

hey, i have a similar issue, i was running Auto mode, and just now switched to manual cause i always thought it was weird my ram was slower than DDR400 when on OC
SOOO
i set the CPU Multipler to 250, ram to 400, but it didnt boot, so i turned it down to 225 to see if it would boot, and it does, but the ram is @ 225, and the FSB is 225, with the CPU @ 29xx (From 2.6) - how do i set the divider in this so i can get higher CPU w/o oc'ing *or as much

* my ram
(it ran at 250 FSB w/o issue, but that was 3:2, as sqaid CPUz)