DRAM Ratio Confusion

[Shamino]

Just to clarify the confusion with straps, base clk and dram frequencies

the only real difference these 3 variables make is in the one variable that actually matters, the DRAM Ratio used.

Up to the 24x which is typically called the 2400 dram ratio, ALL ratios equal or below 24x work equally good at overclocking the DRAM. (that would mean 2400 ratio, 2200 ratios so on)

ALL 100-based ratios > 24x (aka 2600 ratio, 2800ratio, 3000ratio, so on) are NOT good for overclocking, 2600 ratio may boot at 2600dram freq - you may get to 2800 with it but not much more.

30x ratio aka 3000 ratio, gets to 3000 and not much more.

26.66x aka 2666 dram ratio is 133-based but strangely not as good for overclocking - you may get to 2800 with it but not much more.

29.33x aka 2933 ratio seems better than 2666, 3000 seems within reach with it.

32x aka 3200 ratio works good, on par with 24x and below ratios. as an example if i can get 3400 with 24x/below ratios i can be sure 3200 ratio can get the same AS LONG AS PEG/DMI target frequencies is not out of the somewhat limited +/- 5% range.

34x aka 3400 ratio sux, doesnt work well.

Therefore recognize that there is nothing magical about straps or baseclk in relevance to dram frequencies but seperate the 'good' dram ratios from the bad

good: 24x and below + 32x
bad: 26x, 28x, 30x
Barely decent: 26.66x, 29.33x

[Arne Saknussemm]

Shamino bless you I'm sure that's diamond but I'm not sure I understand it

Does that mean I'm better off buying 3200 kit than 3000?

Or that 3000 at 125 bclk is 24 ratio so good...?

[Raja@ASUS]

No - you just run whatever combination of strap and BCLK you need to get either frequency stable.

The "bad" dividers are still "bad", by moving the strap you just end up with the right frequency is all. The strap offset just gets you some of those DRAM kit frequencies that the direct 100 ratios cannot hold stable. Overall you're still running the same "lower and good" divider. You could in fact do it by BCLK with the 100 strap on a good ratio (as per shammy's post).

[chrsplmr]

Threads like this is what I live for .. ROGbits ... thanks guys. .c.

[tistou77]

Thank you for these explanations, although I don't understand everything, with my bad English

[Myk SilentShadow]

Thank you for these explanations, although I don't understand everything, with my bad English

Don't feel too bad mate, English is my native language and I have no bloody clue what the hell he's talking about

[Raja@ASUS]

Its easy Myk. I don't have time to do the whole lot for you but here goes.

Look at what happens to DRAM frequency when you change the strap - the same divider is used. Offsetting the BCLK increases the frequency on the same DRAM ratio!

2400 on 100 strap becomes DDR4-3000 on 125 strap
2133 on 100 strap becomes DDR4-2666 on 125 strap

such ratios are GOOD.


You can apply this to the bad ratios on 100 and find out which frequencies are bad on 125. Look at shammy's post and try it out.


Do this. Set 100 Strap. Select the 2400 ratio. Type in 125 BCLK in the bclk setting. See what it becomes? DDR4-3000. When you go to the 125 strap thats all that happens. We know the 2400 ratio is a good ratio. There for DDR4-3000 on the 125 strap is stable also.


Now if this post does not give you any more insight or idea, I need to find a new job and you guys need to find a new hobby!

[tistou77]

If I understand (with my poor English )

The where is confusing is that I have to mix the strap and BCLK, I think
With X79, I touch only BCLK and DRAM Frequency (Strap = Auto)

Must begin with Strap (BCLK?) 100 and DDR4-2400.
If I would have DDR4-3000, I go up the Strap (BCLK?) to 125?
For DDR4-2800 for example, I have to start 100 BCLK and mount the BCLK until reaching DDR4-2800?

And will 116.6 BCLK (ratio x24)
Is good or not?

Sorry if I didn't understand

[Raja@ASUS]

If I understand (with my poor English )

The where is confusing is that I have to mix the strap and BCLK, I think
With X79, I touch only BCLK and DRAM Frequency (Strap = Auto)

Must begin with Strap (BCLK?) 100 and DDR4-2400.
If I would have DDR4-3000, I go up the Strap (BCLK?) to 125?
For DDR4-2800 for example, I have to start 100 BCLK and mount the BCLK until reaching DDR4-2800?

You can try 100 strap with DDR4-3000. If not stable then use 125 strap and try DDR4-3000.

For DDR4-2800 you can try 100 strap 2666 or 2933 with +/- BCLK.

Or you can use 125 strap and nearest frequency and +/- BCLK to get 2800.

[tistou77]

Ok thank you I will test