What to set Infinity Fabric clock to?

[ripper101]

So I watched this video:

After watching this I was left confused and couldn't really make my own conclusions. 

Right now I have an R7 3700X and Team Dark 3200mhz 14-14-14-31-97 and I currently have it overclocked to 3400mhz 14-14-14-29-43 @1.39v. 

 

My main question is, in my case, what should I set the infinity fabric clock to? For gaming performance what would the best direction be for this kit? 

[BobVonBob]

The conclusion of the video was basically to just crank the fabric clock as high as it can suffer. You can do some minimal performance testing before/after to check if performance has changed after that.

[Jurrunio]

One thing that LTT got wrong: the 1:1 ratio (2:1 option available) is between memory frequency (I/O bus clock) and memory controller frequency (UCLK). Infinity fabric clock is automatically set to be equal to UCLK, though it can also be manually set to something else as you please.

 

16 minutes ago, ripper101 said:

My main question is, in my case, what should I set the infinity fabric clock to? 

1700MHz FCLK, because keeping UCLK = FCLK seems to improve performance compared to having FCLK a touch higher than UCLK (let alone lower). However high FCLK itself can also improve performance. Imo if you can get FCLK to be 266MHz or more greater than UCLK, then keep it decoupled (assuming memory kit can't clock any higher while keeping timings at acceptable range). Otherwise, FCLK should always be equal to UCLK. Never sacrifice UCLK to hit high memory frequency (using 2:1 ratio), nothing good will come out of it.

 

16 minutes ago, ripper101 said:

For gaming performance what would the best direction be for this kit? 

What if you disable Gear Down Mode (which is like 1.5T command rate, compared to standard 1T and 2T) and try raise memory frequency higher at the cost of larger memory timings? You should test how high FCLK can go before it gets unstable before hammering the memory to data rate double that of the FCLK.

[RobFRaschke]

I agree, 1:1:1 MCLK:UCLK:FCLK is your best bet unless you can get drastically higher MCLK. Are you maxed out at 3400mhz? Timings are definitely important, but maxing clock rates is every bit as good. Results at 1800:1800:3600 are great, 1900:1900:3800 are fantastic, even with some looser timings.

 

IMHO with Ryzen in general, crank the clockspeed with speeds synced, then crank down timings as best you can within reason. I wouldn't go much further on voltage though. Some have survived as high as 1.5v without too much issue, but 1.4v is the top of the long term safe voltage for most DDR4 IMHO. 

[ripper101]

22 minutes ago, Jurrunio said:

One thing that LTT got wrong: the 1:1 ratio (2:1 option available) is between memory frequency (I/O bus clock) and memory controller frequency (UCLK). Infinity fabric clock is automatically set to be equal to UCLK, though it can also be manually set to something else as you please.

 

1700MHz FCLK, because keeping UCLK = FCLK seems to improve performance compared to having FCLK a touch higher than UCLK (let alone lower). However high FCLK itself can also improve performance. Imo if you can get FCLK to be 266MHz or more greater than UCLK, then keep it decoupled (assuming memory kit can't clock any higher while keeping timings at acceptable range). Otherwise, FCLK should always be equal to UCLK. Never sacrifice UCLK to hit high memory frequency (using 2:1 ratio), nothing good will come out of it.

 

What if you disable Gear Down Mode (which is like 1.5T command rate, compared to standard 1T and 2T) and try raise memory frequency higher at the cost of larger memory timings? You should test how high FCLK can go before it gets unstable before hammering the memory to data rate double that of the FCLK.

What would be a good frequency to try and achieve? I've seen others get CL14 kits to 3733 MHz 15-15-15-34. Would this be plenty or should I shoot for CL16 at 4000mhz? If I were to go this route would I just leave the FCLK and UCLK to auto?

[Jurrunio]

8 minutes ago, ripper101 said:

What would be a good frequency to try and achieve? I've seen others get CL14 kits to 3733 MHz 15-15-15-34. Would this be plenty or should I shoot for CL16 at 4000mhz? If I were to go this route would I just leave the FCLK and UCLK to auto?

As I said, you should test how high FCLK can go first. The best sample I've seen on ambient cooling is 1933MHz, while 1900MHz is far more common of a good result. Worst result I've seen is 1733MHz