EVGA 680i - Unlinked Bus Problems

[Pax]

Hello all,

I have some problems with the unlinked FSB - memory bus setting behaving strangely, or maybe I just don't understand how it works :rolleyes:.

When setting the FSB to some value, the actual MEM bus follows my changes to the FSB up or down. E.g. if I would change my FSB from 1150 to 1151, the actual MEM would go from e.g. 850 to 851, even though I have specified the MEM should be at e.g. 800. The offset between the FSB and MEM can also be different for different FSB.

Isn't the MEM bus supposed to stay at the value I have given it??

Specs:

P21 BIOS
e6700
2 gig Corsair Dominator 9136
ASUS 8800GTX
SB Audigy 2
2 ATA HDs
1 SATA DVD-RW
1 Floppy
520W OCZ Powerstream

[xgman]

read this carefully. it explains what is happening.

http://www.xtremesystems.org/forums/showthread.php?t=124363

[bachus_anonym]

Unlinked Mode does not give as much independence in choosing memory frequency as many of us probably initially thought. Memory clocking is still based on memory ratios and is FSB dependent, although this time the amount of possible choices (ratios) is significantly higher.

After you set your FSB clock and desired memory clock, the BIOS will calculate a ratio in a way that it will keep your memory frequency suggestion as the upper limit and get as close to it as possible. For example, between 1400-1600MHz FSB there are 8 "chances" of having memory clock set to about DDR2-1300, based on keying 1300 in:

1400MHz FSB --> 7:13
1418MHz FSB --> 6:11
1444MHz FSB --> 5:9
1462MHz FSB --> 9:16
1485MHz FSB --> 4:7
1516MHz FSB --> 7:12
1560MHz FSB --> 3:5
1600MHz FSB --> 8:13

Often, to get exactly the memory clock you want, you will need to adjust your FSB in order for it to stick and fit the ratio that is locked by that memory frequency and starting FSB. Upping FSB, at this particular ratio will eventually reach your desired memory frequency. Once you're there and then decide to still up the FSB, you will force a "RESET" and a ratio change, and in effect effective memory clock will be different from your goal. After that, you will need to raise (or lower) your FSB to get back to your desired memory clock.

I know, kind of lame explanation :lol:

[JoeBar]

I know, kind of lame explanation :lol:
I would call it very useful... :up:

[Pax]

Many thanks guys! :bows:

At first I thought this was buggy BIOS with all that frequency jumping around...

[Eastcoasthandle]

Has anyone checked out this OC guide (http://pc.ign.com/articles/747/747606p1.html) from IGN?

[icon57]

Has anyone checked out this OC guide (http://pc.ign.com/articles/747/747606p1.html) from IGN?
basic n00b guide..imho

[Yoxxy]

There are quite a few ratios though. After going through kind of a test, I counted 16, there may be more.