[SOLVED] Memory Timings not sync 100% to exact value and have decimals.

[kioharumi]

I've used DRam Ryzen Calculator with my DDR4-4000MHz CL16 (F4-4000C16D-32GTRS ). Max with that software is at frequency of 3866MHz. Running at stock DOCP 4000MHz, RAM works fine, but 5900x CPU's FClock won't play nice in my case if i set to 2000MHz (1:1) ratio. System will always have CRITICAL KERNAL error that force restart my PC and sometimes, PC freezed with just pc fan stays ON (no BSOD).

So, i decided to downgrade the RAM to max frequency shown in the calculator (RAM 3866, FClock 1933 = 1:1 Ratio), albeit set SOC, VDDG, cLDO voltages to AUTO instead. Now, after test it with USB's memtest, it is stable and have no error what's so ever.

But, in HWinfo, i realized that the frequency of SDR is not exactly at 1933MHz. It always have extra decimals between 1933.3 to 1933.5 MHz. I had tested Latency benchmark in AIDA64, result always get below 68ns.

Now, my question is, do my system still running at 1:1 Ratio or it's already not synched and actually have performance penalties?

###############################################

My System Specs :


# Cpu : AMD Ryzen 9, 5900x, CCx0 4.7GHz, CCx1 4.7GHz, 1.34v. Single Core Performance 5.15GHz.

# Gpu : MSI Gaming X GTX 1080 Ti, 11GB Gddr5X, 3584 CUDA Cores, oc core clock +111MHz = 2012MHz , Memory Clock +555MHz = 6059MHz

# RAM : Trident Z Royal Silver, DDR4-4000MHz CL16-16-16-36 1.40V, 32GB (2x16GB), Fclk : 2000MHz, Samsung B-Die, F4-4000C16D-32GTRS

# Storage 6.3TB (9=7xSSD+2xHDD) :
Drive #1 - M.2, Samsung SSD 980 PRO 1TB (0025_38B3_11B1_0ACD.) [931 GB] C:
Drive #2 - M.2, KINGSTON SM2280S3G2240G (50026B72670568C9) [223 GB] K:
Drive #3 - INTEL SSDSC2BW180A3L (CVCV333300VH180EGN) [167 GB] I:
Drive #4 - KINGSTON SUV400S37240G (50026B726701B7B5) [223 GB] G:
Drive #5 - WDC WD10EZEX-00WN4A0 (WD-WCC6Y5LRPNJ5) [931 GB] D:
Drive #6 - ST1000DM010-2EP102 (Z9A7QJ70) [931 GB] E:
Drive #7 - KINGSTON SUV400S37240G (50026B766B016A58) [223 GB] H:
Drive #8 - USB External, ADATA HV620 (E50134320654) [931 GB] F:
Drive #9 - USB External, Seagate BUP Slim GD (NA7Z7Q3G) [1863 GB] J:

# Motherboard : x570 Asus ROG Crosshair VIII Dark Hero

# CPU cooler :EKWB EK-AIO DRGB 360

# Fan Case : Arctic P12 PWM PST CO Black 120mm=6, Arctic P14 PWM PST 140mm=2, EK-Vardar EVO 120ER RGB = 3, ID-COOLING 8 PWM & 8 ARGB hub HA-02 (8 Case Fan + 3 EK-Vardar EVO 120ER RGB AiO Fan = 11 Total)

# Case : Lian Li Lancool ii Mesh + 3xAccessories

# PSU : Seasonic Prime Platinum Px-1000, 1000 watt Fully Modular

# Monitor : Dell S2417DG 165hz GSYNC, LG UltraGear lg-27GL650F-B, LG 27MP500-B

# Mouse : Logitech G900

# Keyboard : Corsair K95 Platinum XT + Custom KeyCaps

# Headphone : Sony WH-1000XM4

#Microphone : Antlion ModMic USB

#Others : Custom Black+Red sleeved PSU cable

 

[hotaru.hino]

Don't worry about it. Clock generators on computers don't need to be that precise (this isn't a problem as long as everyone uses the same clock source). The only ones that have to be precise are those that keep time.

 

[kioharumi]

Don't worry about it. Clock generators on computers don't need to be that precise (this isn't a problem as long as everyone uses the same clock source). The only ones that have to be precise are those that keep time.

I mean, my question is not about the system is working or not, i just want to know if there's actually percentage of performance penalties. Since if the Memory timing is not exactly 1933 MHz, and its 1933.5 MHz, DDR value will be 3867 MHz, and infinity fabric clock is 1933MHz ( 1933*2 = 3866 MHz is ideal 1:1 ratio), now, that's not 1:1 Ratio at all.

 

[TommyTwoTone66]

No, you will not lose performance because your memory multiplier is not precisely locked to a specific ratio, the round numbers and ratios don’t mean anything, and in reality the clock speeds involved vary significantly from moment to moment anyway.

The figures displayed in benchmarking tools or bios pages are averages or targets, not fixed performance values. A cpu isn’t like a mechanical clock, things are much more fluid and loose.

 

[TommyTwoTone66]

I mean, my question is not about the system is working or not, i just want to know if there's actually percentage of performance penalties. Since if the Memory timing is not exactly 1933 MHz, and its 1933.5 MHz, DDR value will be 3867 MHz, and infinity fabric clock is 1933MHz ( 1933*2 = 3866 MHz is ideal 1:1 ratio), now, that's not 1:1 Ratio at all.

Well it’s more like 1:1.001, which is close enough to call it optimal. In real world conditions you will see a much larger random variances in ratio just during normal operation even if it was exactly 1000.0mhz/1000.0mhz

Imagine two children on a see-saw, if they weigh the exact same then the balance is optimal. However, if either child moves backward or forward slightly on the seat during normal operation then the balance is not perfect and weight ratio changes throughout operation by a few % naturally.

Over enough time the childrens random backward and forward motion is equal on both sides and the average ratio becomes 1:1, but at any given moment it will not be exactly that since the children will be slightly different distances away from the pivot.