How to syncronize ram & cpu speeds?

[fazi1985]

Hi! I've a P4 2.66/533 cpu with two 512/333 rams in dual channel mode. My question is: how could I sync their speeds? (533 <-> 666) Thx!!!

 

[Scol]

Hmm... Well your CPU is running at 133/533 whereas your RAM is rated for 166/333... I'm guessing your system runs it in ratio anyway, so your setup should be fine.

 

[fazi1985]

And how does this dual ddr works? Does it really doubles clock speeds (666Mhz) ? And what kind of ratio do you mean?

 

[Steg]

Dual DDR simply uses two channals at what ever speed your RAM is running at. So you will have 2 333Mhz channals as opposed to the standard one 333Mhz channal, therefore it doubles the bandwidth. It doesnt actually double the data rate again, but i suppose that would have the same affect.
If you want to sync the speeds i.e. clock the ram down to 133/266 then all you have to do is set the memory/FSB ratio to 1:1 in the bios.
Hope that helps.

Steg

 

[fazi1985]

Changing to 266MHz doesn't cause a drop in performance? What happens if I tune the cpu fsb to 666MHz? It worked fine with 640 (stock cooler) but dunno if it does with 666. And what does 5:4 ratio mean? CPU 5 : 4 RAM or inversely? (<= is this word correct?)

 

[JimShady23]

you can also go out and buy 2x 512 dimms of Corsair PC4200 heh running at 533 mhz.....just a thought.....while your at it get me some too

 

[fazi1985]

A very good idea! My board only supports 333MHz rams, 400MHz with some tuning. So 533 is way to fast for her. But if I OC in bios by 20% (automatic setting), cpu fsb goes at 640 and memory freqy is 200x2=400 + dual channel. Is 640 in sync with 400 or just leave it in 533/333?

 

[JimShady23]

Actually if you can raise the FSB up to 666 mhz and leave the memory clock alone that will be the best sync.......

 

[fazi1985]

666MHz is a bit risky with stock cooling, isn't it? Although it's stable!

 

[JimShady23]

Spend 30 bucks and get a better cooler and stop complaining

 

[Didou]

Your CPU is now running at 133x20 ( 2660 ). Increase your FSB 1mhz at a time or 5mhz if you're confident in your cooling setup. For each speed bump, do a burn test such as the one in Sisoft Sandra or run memtest86 in a loop.

If you reach a speed where your system tends to be a little unstable, try increasing the VCore gradually by 0.01V ( or whatever the smallest increase of VCore your motherboard can provide ).

Increasing the FSB to 166mhz will result in a CPU speed of 3320mhz. It can be reached but you will have to pay a special attention to your CPU temps.

Good luck.

 

[fazi1985]

I'm not complaining! Just trying to reach the optimal performance. Which temp is risky for P4s? (My old 1700+ XP was always around 60-70 °C.)

 

[Didou]

Just make sure it's way below 75°C & you should be fine.

 

[fazi1985]

Anyway is it better running cpu at 666fsb with 333ram speeds than with 400+ speeds? So do syncronized speeds offer better performace than faster, but not sync speeds? (e.g. 666/426 ; if U know what I mean)

 

[JimShady23]

Well

With AMD setups for example.....if you have a XP 2500+ with a 333mhz fsb and you have PC3200 DDR 400mhz, even though the memory is fast, you would get better benchmarks if you were running PC2700 333mhz due to the fact that the fequancy is in sync. Bus speed and memory speed should always be close as possible for best performance

 

[fazi1985]

And so in Intel systems? You mean, I think, running at 666fsb /333ram would be optimal. But I simply cannot set this spec, because raising fsb also effects ram speeds. So 666 fsb causes rams to run at 217*2=437. (ASUS P4P8X) I can't change them one by one! Plz help!

 

[JimShady23]

If I was familiar with Intel overclocking Id be glad to help, no experience OC with them what so ever....I could guess but you wouldnt appreciate that. You will have to wait till you get somone in here that knows what they are doing with intel setups......

You can also try e-mailing Vehementi on this forum. He knows what he is doing with Intel systems.....just look at a couple of trends you are sure to see him there to get his account info.

Love to help but I dont want to offer bad info. Hope I have atleast been with the cpu sync info

 

[Didou]

What you need to do is set the Ram to 1:1 with the FSB. That way, when you raise the FSB to 166, your Ram will be running at its rated speed of 166mhz ( 333 or PC2700 ).

Return the CPU External Frequency (FSB) to 133, then set DRam Frequency to [AUTO] in the BIOS. Boot Windows & see at what speed the Ram is running. If it's running at 133mhz ( 266 ), then it is running in sync with the FSB which is what you want.

You can now resume your OCing. Raise the FSB bump by bump until you reach 166mhz & see if the Ram is indeed running at 166mhz too.

 

[fazi1985]

Thanks for the advices so far! No matter you are an AMD user, i'm sure you can help, just tell me your opinion. And for AMD: how far can I OC my Palonimo 1700+? (<= with a reasonable cooler)

 

[fazi1985]

Thx Didou! But i can't set ratio in bios, i think. I can change dram speed: 266/333/Auto. When set at 333 and fsb OCed to 666, ram speeds also change, dont stay at 333. Dunno what to do!

 

[Didou]

Set the DRam speed to 266 then. What happens when you raise the FSB with it set to that setting ?

 

[fazi1985]

I'll do, but 666fsb - 434ram? Why 434? It's not logical!

 

[Didou]

I don't know why it is set to 434. If you set the DRam Frequency to [333], I suppose it's using a 5/4 ratio with the FSB. So when your FSB is set to 133, 5/4 of that FSB will result in 166.

When you raise the FSB to 166 with the same ratio, the ram should be running at 207 ( 414 ) but I don't see where 434 comes from.

 

[fazi1985]

Maybe you're right with 207. I don't remember. I'll try! Well, where do you live? It's 6.32pm here at the moment.