200Mhz to 133Mhz (???) RAM

[PDH-NicFury]

I pump my 'FSB' to 300Mhz to get a 3Ghz cpu speed using an Opteron 170 and ASUS A8N32SLI. What gets me is my RAM drops from 200Mhz to 133Mhz. I've been trying to understand all this cpu to memory ratio, DDR skew, memory timings, RAS, CAS, FAS, ZAS, HAS, MYASS... GOING CRAZY! It sure seems to have backed off a lot, want to know how to get it back up to a faster speed, think I'm getting shortchanged with my memory settings on auto. (Been trying to find as much as possible on this memory settings stuff, most of it reads like real tech-babble...)

Who wants to take a stab and put down how to tweak memory to maximize performance when overclocking the cpu (fsb)? ... I'm talkin' oc'ing for dummies, here...

PDH-NicFury

 

[Pain]

Without trying to be rude, but probably being rude anyway, I think if you don't understand these things then you shouldn't be doing it until you read about it more.

If the memory is set to auto, then most likely it is trying to keep the memory at the default speed. It is probably showing the memory at 133, but it is really a ratio based on the actual FSB speed, so it is reducing the memory speed to keep it at it's rated speed.

I'm not going to get into specifics because there is more to it than that, and plenty of sites that talk about it much better than I could in a forum post. But, yeah, if you change it from auto to manual you can run it at what ever speed you want, but keep in mind you may end up with an unstable system and might do some damage, which more than likely would be in form of a corrupted data.

 

[PDH-NicFury]

Let me put forth a little more info:
the timings are 3-3-3-8, 133Mhz
before pumping fsb: 3-3-3-8, 200Mhz
rating is 2-3-3-6 out of the box (will work on timings another day...)
It is Corsair XMS PC-3200C2, so I would imagine that it might actually overclock decently.

From what I read, the best ratio is 1:1, meaning if I put the 'fsb' to 300Mhz, then the RAM should also be 300Mhz. (Stock is 200Mhz for the mobo/cpu and 200Mhz for the memory, so I get a 1:1 ratio.) Something tells me this is not a good idea to push RAM to 300 if stock speed is 200, but lowering down to 133 doesn't seem right either. The current ratio is approximately 2.25:1 (9:4). Am I understanding it wrong, should the memory go down as the fsb goes up??

PDH-NicFury

PS: Thanks for the comments, but what I can do I will do... and my rig is a hell of a lot faster with what I have currently done :!: :twisted:

 

[Pain]

Let me put forth a little more info:
Why is it going back? Is it a double data rate thing, or dual channel thing?

Neither. It is likely the fact that it is trying to protect you from yourself.

1:1 is definitely best, which means the memory and FSB are running syncronously, i.e. at the same speed.

I admit I don't know that much about the new boards so I have to stay out of it from this point. But, I'm curious if you mean you have set the FSB to 150, not 300? If you are using pc3200 memory then there is no way it is going to run at 300 (i.e. 600). So, I'm confussed.

I think what is happending is that the board is forcing the memory to 2/3 ratio. It can't display the frequency correctly so it is showing the memory speed at 133, with is 2/3 of 200. 200 is 2/3 of 300, so the ratio is the same, and the memory is running assyncrounsly to the cpu, but at the rated speed of the memory which is 200 (400)

But, again, I know nothing of that board, so I'm guessing.

 

[bombasschicken]

what mobo you got.. thats a start..

also relaxing the timings on the ram helps a little.. i had the problem before.. i upped my FSB but my ram droped to 2:1.. so my ram was running at half speed.. i tried to force it to 1:1 but it wouldnt boot.. so i relaxed the timings (generously) and i was able to get 1:1.. its really touch and go.. just play with it a little till you get it going..

 

[PDH-NicFury]

No error there, the 'fsb' is at 300. Mobo is ASUS A8N32SLI.

Not quite sure how you came up with the 2/3 ratio... again, you're going lower with the memory while the 'fsb' is going higher. If the ratio were indeed 2/3 (or 3/2 fsb to memory), the memory wouldn't have gone down but stayed the same. Either that, or I'm not understanding your explanation and require a further breakdown of the relation of the fsb to memory ratio.

PDH-NicFury

 

[Pain]

You're not understanding me becasue I'm not explaining it well. 2/3, 3/2, whatever. The fact is that if you fsb is running at 300 there is likely no way the memory will work at that freq, so it is reducing it to 200. 200 is 2/3 of 300. 133 is 2/3 of 200, so it is showing you 133, which relates to the ratio 2/3 of the current fsb, which is 300. The current fsb is 300, so 2/3 of 300 is 200 which is where the board wants to run the memory. So, in this case 133 = 200 Confused? I am.

Anyway, the fact remains, you in all likelyhood will not be able to run the memory at 300. You can try by setting it manually instead of auto, but like the guy said above you will probably have to relax the timing a lot. Might also have to raise the voltage too.

 

[PDH-NicFury]

Where's Triple-M (MadModMike) when you need him...

 

[Covered_in_bees]

Can I have a go at explaining this :?:

I have the same motherboard as you, and also the same cpu. Can't say I have the same OC though

Anyway, what's happening is that, as you increase the fsb, the motherboard is automatically reducing the Memory CLK. This is because the motherboard recognises from the SPD that the memory is rated at 200MHz, and will reduce the Memory CLK to ensure that the memory is operating at or near it's rated frequency (this happens when the Memory CLK is not set manually).

The way to set dividers on this board is to set the Memory CLK manually. The board has the following options:

200 = 1:1
166 = 5:4 (almost)
133 = 3:2
100 = 2:1

These ratios/dividers are calculated against the stock 200 MHz fsb frequency

fsb frequency (200) : Memory CLK value in bios

So, if you have the Memory CLK at 133, the ratio/divider is 3:2. However, when setting the Memory CLK, what you are really doing is defining the ratio between the fsb and the memory frequency.

So, if you then increase the fsb to 300, then the memory frequency increases based on the above ratio/divider, and is actually running at:

300 / 3 * 2 = 200 MHz

If you want to try a different divider, then you need to set the Memory CLK manually in bios.

At Memory CLK 166, the ratio/divider is 5:4, and the memory will therefore run at 300 / 5 * 4 = 240MHz

I'm not sure if I've made this any clearer, but at least I tried

 

[Pain]

That's what I said.

 

[Covered_in_bees]

I know - I just took your words and rearranged them :lol:

 

[PDH-NicFury]

I'm really trying to understand the help you guys are giving me...

I think what my problem is concerns the '133' Mhz... I don't see why the BIOS lists it as such when by your equations it is still '200' Mhz.

Wait... scheisse... I think it just hit me... :idea:

Instead of showing the actual memory clock speed, it's showing the ratio'd clock speed if the 'fsb' was still at 200Mhz (which I think was already stated), is this the case?

Edit: This of course raises other questions...

The BIOS lists the memory clock at 133Mhz; is this the actual speed it is working at or is it still working at the stock 200Mhz? From what you've said so far, I would think (probably wrongly) that the memory is working at 200Mhz.

 

[Covered_in_bees]

I'm really trying to understand the help you guys are giving me...

I think what my problem is concerns the '133' Mhz... I don't see why the BIOS lists it as such when by your equations it is still '200' Mhz.

Wait... scheisse... I think it just hit me... :idea:

Instead of showing the actual memory clock speed, it's showing the ratio'd clock speed if the 'fsb' was still at 200Mhz (which I think was already stated), is this the case?

You got it !!

Don't ask me why they implemented it this way - maybe they don't expect ppl to change the fsb

Edit: This of course raises other questions...

The BIOS lists the memory clock at 133Mhz; is this the actual speed it is working at or is it still working at the stock 200Mhz? From what you've said so far, I would think (probably wrongly) that the memory is working at 200Mhz.

Currently your memory is working at 200MHz with your fsb at 300 and the bios reporting memclock at 133.

Best way to check if your still unsure - run CPU-Z in windows and check the memory tab - it will tell you the actual operating frequency and all the timings.

 

[PDH-NicFury]

Thanks, dude... for a while I thought I was going to go insane. 8O Whoever thought that up should be taken out back and beat to death with a whiffle-ball bat.

If you're still around, 'Covered in bees', read the edit, still need that last piece of the puzzle...

Thanks again,
PDH-NicFury

Edit: my brain is fried, I just re-read my post and answered my own question... :roll:

Right on, right on...

 

[Covered_in_bees]

I edited my response also

 

[PDH-NicFury]

Wilco

Edit: (I love editing...) :arrow: OK, now that we have that figured out, if I shrink the divider, then I am, in effect, overclocking the RAM (?). True or false??

Another thing I was wondering, what is the purpose of buying RAM rated above suggested manufacturer RAM, i.e. PC-3500 or higher instead of PC-3200? Is this to bypass the possibility of destroying RAM in an attempt to overclock it since it's already at a higher clock speed?

PDH-NicFury

What I wouldn't do to have the brain of Nikola Tesla without the quirks...

 

[drkspidr]

PDH-NicFury

Try this guide:

http://www.short-media.com/review.php?r=300&p=3

It pretty much explains everything you need to know about overclocking your system.

BTW, I have that same motherboard and CPU.

Just increasing your FSB setting is not going to help you. At best you will have stability issues, and at worse damaged hardware.

I purchased the 170, the Asus A8n32 and Corsair DDR500 RAM for a very simply overclocking equation:

CPU Multiplier x 10
FSB Change from 200 to 250
HTT Multiplier from 5 to 4

So I get a 25% overclock without having to do any shenanigans. That's right, I said it, shenanigans.

I'm amazed that your system booted at a FSB change to 300 without any other adjustments. It could be that if you did not disable Cool and Quiet that even though you set the FSB to 300, your CPU automatically throttled down to a x8 or even x7 multiplier, as well as scaling back your memory.

Dark Spider

 

[Covered_in_bees]

OK, now that we have that figured out, if I shrink the divider, then I am, in effect, overclocking the RAM (?). True or false??

If you up the memclock to 166MHz, then you will increase the actual frequency to 240MHz. However, realistically, this is not a good idea.

When overclocking, what is normally done is to drop the cpu multiplier, and then starting with the fsb back at 200, increment slowly to find the max overclock of the memory using a 1:1 divider.

You would then compare that to the max overclock of the cpu, and come to a decision on the optimum settings.

With your memory, it's very unlikely you will be able to run it at 240MHz. I would suggest that, with the fsb at 300, 133 memclock is tbe best setting. You could try and improve the timings to get a bit more performance out of it.

Another thing I was wondering, what is the purpose of buying RAM rated above suggested manufacturer RAM, i.e. PC-3500 or higher instead of PC-3200? Is this to bypass the possibility of destroying RAM in an attempt to overclock it since it's already at a higher clock speed?

The reason for buying memory that is capable of running at a higher clock frequency is so that, when overclocking, you can maintain 1:1 divider. For example, if your memory was capable of running at 300MHz, then you could leave the memclock at 200MHz, up the fsb to 300MHz, and have your memory running at 300MHz.

Just a question - if your running with your fsb at 300, have you dropped the cpu muliplier to x9 on that Opteron 170 ?

 

[PDH-NicFury]

Um, uh, ... no 8O

I have a Swiftech watercooling rig going, cpu and video cards. 8) Yep, the fsb is at 300, the mem divider is at ... anyway, the mobo clock says 166 for mem, and cpuz says... hold on while I look... 250Mhz.

Yep, trying to avoid meltdown while looking for the holy grail of (my cpu's) overclocking potential and stability. I manually pulled back the mem timings to 3-4-4-8, and so far ... not bad, but still gotta work out some issues. (I'm writing all this with the above settings.)

Thanks for the help, Cob, and I'll look at that link later to see what they have to say on oc'ing.

PDH-NicFury

Making the world unsafe, nuking one rig at a time (all in the pursuit of excellence...)

 

[Datman]

http://www.obm.co.nz/OBMNew/800x600/guides/ddrram.htm

Some info on memory, might help.

 

[PDH-NicFury]

Alright, after trying different settings, I've come to realize that getting 3Ghz on my Opty170 ain't gonna work... at least with 3:2 divider, much less 5:4. The 5:4 bumps my memory a little too high, get errors left and right with memtest86.

Now for the next question: I know that you want as close to 1:1 (if not 1:1) ratio as possible... but what if I went 2:1 and pumped the 'fsb' with a lower cpu multiplier. Overclocking the memory would be a bit more flexible (read 220-230 instead of 240+Mhz). Would this help stabilize the overclocked cpu/fsb, or would I just be heading for a meltdown?

Gimme some feedback, guys :!:

PDH-NicFury

Making the world unsafe, nuking one rig at a time (all in the pursuit of excellence...)

 

[PDH-NicFury]

Alright, update and question time! :!: :roll:

I can run my rig at 300 fsb (htt) with memory at 200Mhz/ 3-4-4-8 and it works fine... except when stress testing. Prime95 and Memtest86 both go bad in a short amount of time. I can play Halo for hours, but I don't think that counts for much of a stress test. (Sure runs smooth, though.)

I know I asked this before, but time to do it again.

I'm thinking of grabbing PNY Verto DDR600 memory, that way I can keep a 1:1 ratio for fsb:mem. Theoretically this should solve my problems, or am I just wishing? Start opinning guys, let me know if this is a good idea or just stick with my DDR400 and keep tweaking until I get my PC stable.

PDH-NicFury :?

 

[Pain]

What you buy is up to you, but I will say that if you get errors in the tests, prime95 or memtest86, then your system isn't stable and you are asking for corrupt data. It may never happen, but you're still playing with fire.

Oh, and BTW, you really aren't sure if it's the memory causing the errors, or the overclocked CPU so if it were me I'd get it running perfectly stable with the stuff you have right now before I add another variable to the mix.

 

[PDH-NicFury]

Wusy:
The RAM is rated at 3-3-3-8 for 200Mhz, tighter timings if I drop to 166 or 133 speeds...

 

[PDH-NicFury]

Wusy,
Should I run the RAM at 2-3-2-6 1T at stock cpu speed or should that also work if I overclock (say, to 3GHz from 2GHz)?

PDH-NicFury :?: