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DRAM Ratio Confusion

Shamino
Moderator
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
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29 REPLIES 29

Arne_Saknussemm
Level 40
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
Level 13
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
Level 18
Threads like this is what I live for .. ROGbits ... thanks guys. .c.

tistou77
Level 13
Thank you for these explanations, although I don't understand everything, with my bad English 🙂
Sorry for my english 😄


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tistou77 wrote:
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
Level 13
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! 😄

Raja@ASUS wrote:
... 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! 😄

hahahhaa ~bows to Raja~ [.. don't even think about it .. you will never be allowed to return to your home planet.]
.. that said .. Thank you goodSirs. .c.

Raja@ASUS wrote:
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! 😄


OK...so I just re-read this and finally understood it 😮

Since this thread started RAM frequencies have obviously moved onwards and upwards from the range discussed....what are the good ratios for frequencies north of 3200?

Arne Saknussemm wrote:
OK...so I just re-read this and finally understood it 😮

Since this thread started RAM frequencies have obviously moved onwards and upwards from the range discussed....what are the good ratios for frequencies north of 3200?


Not just that, but there have been a lot of BIOS "ram compatibility" changes since this post originated so how much is still true?

Honestly, the DDR4-X at BCLK 100 equals DDR4-Y at BCLK 125 always made sense to me. What I can't wrap my head around is what "bad" means.

I stick with the 100 strap because I want adaptive CPU voltage to work. For 24/7 operation that's a requirement. I'm also running DDR4-2800. It seems to run just fine. What am I missing? Since it seems to work without errors, what's so bad about this ratio?