asrock x99 can't set ddr4 to 2800 with xmp profile

[dloweinc]

Hi there,

I am trying to set my Corsair Vengeance DDR 4 memory to its 2800mz speed but when I do it sets the bclk to 127.3, which sets the CPU to 4459mhz... I don't want to overclock my CPU that much, if at all, just want my memory to run at its advertised speed.

I was reading that the ASUS boards set the strap? to 125 so the blck of 127.3 doesn't affect the CPU or other things so badly, but I don't see any such setting to change (nor do I think I should have to change it to be honest).

I have bios version 1.30
corsair ddr4 is: CMK16GX4M4A2800C16 4GB x4

This is on the asrock x99 ws board

Any help would be greatly appreciated. By default the system runs fine with RAM at 2133mhz, but these are 2800mhz sticks and I'd like to get that speed.

(BTW this RAM is on their QVL list)

[parsec]

Re: asrock x99 can't set ddr4 to 2800 with xmp profile

I've read that all X99 boards, meaning made by all manufactures, will increase the BCLK with any memory whose speed is over 2133. The maximum guaranteed memory speed of Haswell-E processors is 2133 (Intel spec) so the change in BCLK with memory above that speed may be a necessity.

You can change options in the BIOS to compensate for the increased BCLK. There are two you'll need to change, CPU Ratio and CPU Cache Ratio, found in the OC Tweaker screen. The CPU Ratio is also known as the CPU Multiplier, so ratio and multiplier are the same thing.

In case you don't know, CPU speed/frequency is determined by the CPU ratio and BCLK. CPU frequency = BCLK X CPU ratio.

In terms of CPU ratio, CPU ratio = CPU frequency/BCLK.

Assuming the BCLK will be set to 127, you can choose the CPU frequency/speed you want to have, and divide that by 127 to find the appropriate ratio/multiplier.

A CPU speed of 3.5 GHz would have a CPU ratio of 3500 / 127 = 27.559. CPU ratio must be an integer value, so round up or down to 28 or 27.

The CPU Cache speed is normally identical to the CPU speed, so its ratio (or multiplier) is the same as the CPU ratio. Over clocking the CPU cache does not increase performance as much as over clocking the CPU cores, so the CPU cache ratio does not need to be identical to the CPU ratio, but it can be.

The closest setting to the strap that you mentioned is the BCLK/PCIE Ratio in the BIOS. I cannot predict its behavior and affect on memory speed, so you'd need to experiment with that option to discover if it will help.

[dloweinc]

Re: asrock x99 can't set ddr4 to 2800 with xmp profile

I've read that all X99 boards, meaning made by all manufactures, will increase the BCLK with any memory whose speed is over 2133. The maximum guaranteed memory speed of Haswell-E processors is 2133 (Intel spec) so the change in BCLK with memory above that speed may be a necessity.

You can change options in the BIOS to compensate for the increased BCLK. There are two you'll need to change, CPU Ratio and CPU Cache Ratio, found in the OC Tweaker screen. The CPU Ratio is also known as the CPU Multiplier, so ratio and multiplier are the same thing.

In case you don't know, CPU speed/frequency is determined by the CPU ratio and BCLK. CPU frequency = BCLK X CPU ratio.

In terms of CPU ratio, CPU ratio = CPU frequency/BCLK.

Assuming the BCLK will be set to 127, you can choose the CPU frequency/speed you want to have, and divide that by 127 to find the appropriate ratio/multiplier.

A CPU speed of 3.5 GHz would have a CPU ratio of 3500 / 127 = 27.559. CPU ratio must be an integer value, so round up or down to 28 or 27.

The CPU Cache speed is normally identical to the CPU speed, so its ratio (or multiplier) is the same as the CPU ratio. Over clocking the CPU cache does not increase performance as much as over clocking the CPU cores, so the CPU cache ratio does not need to be identical to the CPU ratio, but it can be.

The closest setting to the strap that you mentioned is the BCLK/PCIE Ratio in the BIOS. I cannot predict its behavior and affect on memory speed, so you'd need to experiment with that option to discover if it will help.

Thanks, it didn't even occur to me to lower the ratio, I will try that.

I did try to mess with bclk/pcie ratio that didn't help. I added some voltage too cpu and I could post but Windows blue immediately.

I'll update after tomorrow.

[ASRock TSD - Emily]

Re: asrock x99 can't set ddr4 to 2800 with xmp profile

Hi Dloweinc,

I did the test with the following configurations, and the CPU frequency still works at the default frequency.
System won't automatically overclock CPU more than 4GHz or higher frequency.
Motherboard: X99 WS
BIOS: P1.30
CPU: i7-5820K
Memory: Corsair CMK16GX4M4A2800C16
VGA: HD6450

Please refer to the following steps to load XMP Profile and then check the CPU frequency again.
Step 1. Only set "Load XMP Setting " at [Profile1 DDR4-2800] under DRAM Configuration page.
Step 2. And then press "F10" to save the settings and exit BIOS setup.
Step 3. After rebooting system, please enter to BIOS setup and check the current CPU frequency.
Please refer to the picture as below, the CPU frequency works at [3312MHz] when loading XMP profile DDR4-2800.


Please follow the steps as above to try agian.

If any question, please feel free to let us know.
Thank you very much!

[dloweinc]

Re: asrock x99 can't set ddr4 to 2800 with xmp profile

This did work. For some reason you HAVE to go into the bios again after selecting xml 1, hitting f10 and rebooting. If i didn't it hangs.

Of course now my 5930 cpu is 3312Mhz instead of 3500Mhz. I am not sure which one is very to have.

[ASRock TSD - Emily]

Re: asrock x99 can't set ddr4 to 2800 with xmp profile

Dear dloweinc,

Sorry for the CPU frequency issue.

Our BIOS R&D team released a BIOS L1.33 to revise i7-5930K CPU frequency issue.
Please download the BIOS files from the following link.
Link: http://we.tl/bsL4sf3fDC (This is a trusted link, please don't worry about it.)
We'll upload the BIOS to the beta zone on our website later.

In this BIOS, CPU i7-5930K will work at 3567MHz after loading XMP Profile DDR4-2800.
Please test the BIOS and then share your test result with us.

If you have any question or suggestions, please feel free to let us know.
Thank you very mcuh!

[dloweinc]

Re: asrock x99 can't set ddr4 to 2800 with xmp profile

I was able to load the xmp 1 profile and it works ok, but the system seems to be slightly unstable. I have had a freeze, a reboot and a blue screen since using that profile. So for the time being I am back on bios defaults.

I don't know if my cpu is below average, but it didn't seem to want to go above 3.5Ghz at all. (All crashes etc above were not OC'd)

My specs:
CPU: Core i7 5930
Motherboard: Asrock x99 WS
CPU Cooler:Corsair h105 (45c under full load)
RAM: 16GB corsair vengeance
Power supply: Evga 1000w platinum
Case: Corsair carbide 540
OS: Win 8.1 pro
GPU: Nvidia gtx 780

[ASRock TSD - Emily]

Re: asrock x99 can't set ddr4 to 2800 with xmp profile

Hi dloweinc,

I tested the same memory modules with the following configuraiton, and system can work at DDR4-2800 stably.
When system is under full loading, the CPU temperature is around 55 degree C.

System Configuraiton:
M/B: X99 WS
CPU: i7-5930K
Memory: Corsair CMK16GX4M4A2800C16 (4GBx4)
Cooler: CoolerMaster water cooling
OS: Windows 8.1
BIOS: L1.33
Test Program: Prime95 and MemTest

System run Prime95 test over 3 hours and Memtest for 1 loop are passed at our side.


Please refer to the following suggestions to do the test again.
1. Please load default settings and only load XMP Profile 1 to check whether system works at DDR4-2800.
2. Please only install one or two sticks memory modules to check if the symptom still occur.
If not, please install one stick memory by turns to check whether one of them couldn't run at DDR4-2800 stably.
3. You can try to set CPU Ratio at [26] or [27] manually and then clarify if the symptom is relalted to CPU or memory modules.
4. If you have another X99 Platform, please help test the memory on another system to check if the memory modules can work at DDR4-2800 flawlessly.
5. If you have another DDR4-2800 memory, please test them on X99 WS to clarify the possible reason.

If you have any question or suggestions, please feel free to contact me.
Thanks for your test result and quick response!