What is FCLK Frequency and is it fine set at "Auto"?

[RunningRathian]

I have a 5800x rated at 3800mhz (obviously), with a B550-F motherboard and Corsair Vengeance 4x8 ddr4-3600mhz ram. I was running Heaven Benchmark and saw that it said my cpu frequency was 3799mhz, which confused me. so I checked HWInfo and CPU-Z for my frequency, and both had different results; HWInfo would be saying the clock speeds are fluctuating like normal at 3700mhz while CPU-Z is hovering around 3599mhz (I assume none of this is peculiar? I assumed the cpu frequency being listed at 3799mhz is sort of like how the memory frequency isn't EXACTLY 3600mhz, but has a slight deviation instead)

 

anyway, for peace of mind, I just went into the Bios to check my CPU Frequency and saw FCLK Frequency. I briefly read up on what it was related to and it has to do with Ram. I don't necessarily want to look into overclocking but I recently updated my chipset drivers for the board and although I highly highly doubt the chipsets can alter Bios settings, I got concerned over whether or not this FCLK Frequency has always been set to "Auto" or not. I have DOCP enabled ofc, but is FCLK fine to just stay on Auto? I presume that's the stock setting and is perfectly fine/stable on Auto with xmp, newest chipsets, etc.

[RONOTHAN##]

5 minutes ago, RunningRathian said:

I got concerned over whether or not this FCLK Frequency has always been set to "Auto" or not.

It is. The default behavior is to remain equal to the memory clock (half the advertised data rate because RAM is double data rate) up until you get to DDR4 3600, then the FCLK will stay at 1800MHz unless you manually set it above that. Ideally you want the memory clock equal to the FCLK for some technical reasons, so auto is perfectly fine with 3600MT/s RAM. I generally set it manually just in case the board does some weird stuff with it, but that's rare enough that I would hardly say it's necessary. 

 

The FCLK is also known as the Infinity Fabric if you've heard of that in reference to AMD CPUs. It's the interconnect between the different CPU dies and the IO die for the memory controller. 

 

12 minutes ago, RunningRathian said:

I have a 5800x rated at 3800mhz (obviously), with a B550-F motherboard and Corsair Vengeance 4x8 ddr4-3600mhz ram. I was running Heaven Benchmark and saw that it said my cpu frequency was 3799mhz, which confused me. so I checked HWInfo and CPU-Z for my frequency, and both had different results; HWInfo would be saying the clock speeds are fluctuating like normal at 3700mhz while CPU-Z is hovering around 3599mhz (I assume none of this is peculiar? I assumed the cpu frequency being listed at 3799mhz is sort of like how the memory frequency isn't EXACTLY 3600mhz, but has a slight deviation instead)

Can you send a HWInfo log file? There shouldn't be that big of a swing between CPU-Z and HWInfo, and even then it should be boosting well beyond 3.8GHz when running something like Heaven (one core should be up near 4.8GHz, give or take). 

[WereCat]

It's the frequency of the Infinity fabric that controls the communication between the CPU dies and the IO die.

If you leave it on AUTO it should default to your DRAM frequency but maxes out at 1800MHz (so 3600MT/s DRAM) so if you had faster memory kit you would need to adjust your FCLK manually to get it to higher speeds and match your DRAM frequency.

 

It can greatly affect the performance so you ideally want the FLCK to match your DRAM frequency so that they are in sync.

That said, there is FCLK, MCLK, UCLK and they should be all in sync for the best results.

 

You can get something like Zen Timings and check that.

 

 

[RunningRathian]

28 minutes ago, RONOTHAN## said:

It is. The default behavior is to remain equal to the memory clock (half the advertised data rate because RAM is double data rate) up until you get to DDR4 3600, then the FCLK will stay at 1800MHz unless you manually set it above that. Ideally you want the memory clock equal to the FCLK for some technical reasons, so auto is perfectly fine with 3600MT/s RAM. I generally set it manually just in case the board does some weird stuff with it, but that's rare enough that I would hardly say it's necessary. 

 

The FCLK is also known as the Infinity Fabric if you've heard of that in reference to AMD CPUs. It's the interconnect between the different CPU dies and the IO die for the memory controller. 

 

Can you send a HWInfo log file? There shouldn't be that big of a swing between CPU-Z and HWInfo, and even then it should be boosting well beyond 3.8GHz when running something like Heaven (one core should be up near 4.8GHz, give or take). 

it's not a log file but I can send a screenshot

 

that's what HWInfo does during the benchmark. for context, I do have mostly Moderate settings on HB, as well as 60fps cap and Vsync. I also have Eco Mode 65w on the 5800x while I wait to eventually get a better cooler

 

here is CPU-Z in the same benchmark. (bad timing, the Core Voltage number must have flickered; it was at a normal number that I've always seen on this pc)

 

my "Frequency Limit- Global" in HWInfo also drops and floats around under load. it's usually 4850mhz on idle but then it can drop 4840 and lowest I saw it on Cinebench was 4681; not sure if this last part is relevant. but there's the screenshots of CPU-Z and HWInfo during HB, lmk if you want to see the clocks on idle, I'll attach them too

[RONOTHAN##]

10 minutes ago, RunningRathian said:

that's what HWInfo does during the benchmark. for context, I do have mostly Moderate settings on HB, as well as 60fps cap and Vsync. I also have Eco Mode 65w on the 5800x while I wait to eventually get a better cooler

OK, those numbers make sense for a 60FPS cap and a low power limit. 

 

10 minutes ago, RunningRathian said:

here is CPU-Z in the same benchmark. (bad timing, the Core Voltage number must have flickered; it was at a normal number that I've always seen on this pc)

 

OK, that can be explained by the refresh rates for each application being slightly different as the CPU frequency will float around a bit. It's close enough to one of the cores current frequency that it doesn't really surprise me. If you load up an all core workload like Cinebench, the frequency should end up being more constant across all cores and the different reported frequencies should line up between CPU-Z and HWInfo. 

 

18 minutes ago, RunningRathian said:

my "Frequency Limit- Global" in HWInfo also drops and floats around under load. it's usually 4850mhz on idle but then it can drop 4840 and lowest I saw it on Cinebench was 4681; not sure if this last part is relevant. but there's the screenshots of CPU-Z and HWInfo during HB, lmk if you want to see the clocks on idle, I'll attach them too

The frequency limit has something to do with PBO IIRC, for the most part I'd just ignore it since it doesn't really seem to relate to anything performance wise in my experience. 

[RunningRathian]

14 minutes ago, RONOTHAN## said:

OK, those numbers make sense for a 60FPS cap and a low power limit. 

 

OK, that can be explained by the refresh rates for each application being slightly different as the CPU frequency will float around a bit. It's close enough to one of the cores current frequency that it doesn't really surprise me. If you load up an all core workload like Cinebench, the frequency should end up being more constant across all cores and the different reported frequencies should line up between CPU-Z and HWInfo. 

 

The frequency limit has something to do with PBO IIRC, for the most part I'd just ignore it since it doesn't really seem to relate to anything performance wise in my experience. 

loaded up Cinebench real quick; HWInfo core clocks were at 4.124mhz while CPU-Z core clocks were fluctuating a bit more between 4.099mhz and ~4.121mhz. when the render cycle starts over, that's when it seems to deviate the most, with HWInfo remaining roughly at the same clocks, while CPU-Z stays at a lower clock for a bit before coming back up to 4.11mhz. this is a more acceptable deviation, right?

 

I think Eco Mode stops the clocks from going to a full 4.8mhz, not sure though. but under Cinebench with my current settings, the clocks are anywhere between 4.1-4.5, depends on when I do the benchmark really. I'm not an overclocker or someone who tries to squeeze a ton of performance from my pc, I just don't want anything to become unstable or concerningly low/high; in games, I don't feel too affected by my core speeds, which can be anywhere from 3.7-4.2

[RONOTHAN##]

24 minutes ago, RunningRathian said:

this is a more acceptable deviation, right?

Yeah, that seems fine enough. 

 

24 minutes ago, RunningRathian said:

I think Eco Mode stops the clocks from going to a full 4.8mhz, not sure though. but under Cinebench with my current settings, the clocks are anywhere between 4.1-4.5, depends on when I do the benchmark really. I'm not an overclocker or someone who tries to squeeze a ton of performance from my pc, I just don't want anything to become unstable or concerningly low/high; in games, I don't feel too affected by my core speeds, which can be anywhere from 3.7-4.2

Yeah, Eco mode definitely isn't helping. 4.8GHz is only for single thread workloads though (single thread Cinebench), not multi core. Your multi core clocks are right where I'd expect them for Eco mode. 

[RunningRathian]

9 minutes ago, RONOTHAN## said:

Yeah, that seems fine enough. 

 

Yeah, Eco mode definitely isn't helping. 4.8GHz is only for single thread workloads though (single thread Cinebench), not multi core. Your multi core clocks are right where I'd expect them for Eco mode. 

ahhh, that makes a lot more sense. Single Core on Cinebench with my current settings has most of my cores at 3.8-4.0ghz, with 1 of them at 4.7-4.8, and the other hovering close to that area as well; I thought it was purely Eco Mode reducing the Multi Core load, but that clears it up

 

 

I know Eco Mode isn't the greatest thing to have enabled for performance, but by itself, it hasn't really tanked my performance in noticeable ways, so that's what matters for me (outside of benchmark scores obviously)