i7-5820 & Asrock x99 Extreme 4 : memory bus speed affects stability

magellan · Jun 30, 2015

I've had major problems getting my i7-5820 overclock stable and had pretty much given up until I tried manually setting the DRAM frequency to 133 MHz as opposed to 100 MHz. I tested this by running the exact same BIOS settings except for the DRAM frequency and noted that even at nearly the same DRAM frequency (say 2400 MHz) the system was unstable when using the 100 MHz DRAM frequency as opposed to the 133 MHz DRAM frequency. This instability was such that the system was unbootable when set at the 100 Mhz DRAM frequency and 2400 MHz (by manipulation of the multiplier). I now believe the AUTO setting for DRAM frequency is using 100 MHz.

Has anyone else come across this weird issue?

EarthDog · Jun 30, 2015

Long time no see!

Update your signature with the right hardware at your earliest convenience. That will help in troubleshooting if we know the exact parts you have.

I set my memory via the XMP profile and it is stable. Have you tried that as opposed to manually setting things as you seem to have done? Typically one doesn't touch the memory straps like that. I have not experienced that behavior on any X99 based board though when I do set things manually. Actually, it is left on auto come to think of it.

magellan · Jun 30, 2015

EarthDog said:
Long time no see!

Update your signature with the right hardware at your earliest convenience. That will help in troubleshooting if we know the exact parts you have.

I set my memory via the XMP profile and it is stable. Have you tried that as opposed to manually setting things as you seem to have done? Typically one doesn't touch the memory straps like that. I have not experienced that behavior on any X99 based board though when I do set things manually. Actually, it is left on auto come to think of it.

ED, for both tests (w/the DRAM freq. set to 100 MHz and 133 MHz) I didn't change any other settings except the RAM multiplier to make sure the RAM frequency was approximately the same for each test.

I had thought the RAM frequency was determined by the BCLK and a RAM multiplier? So what does the DRAM freq. setting do?

EarthDog · Jun 30, 2015

Post a screenshot of your bios with that setting you are asking about...

Did you try xmp with everything else on auto?

trents · Jun 30, 2015

I've read where changing the memory strap can help give more room to tweak with the FSB on the Intel APUs.

magellan · Jul 1, 2015

ED, is the only way to get screenshots of the BIOS settings
to take a photo? Or is there a way to save a screenshot of BIOS
settings to a USB HDD?

EarthDog said:
Post a screenshot of your bios with that setting you are asking about...

Did you try xmp with everything else on auto?

- - - Updated - - -

This does seem to be the case w/my i7-5820 and Asrock x99 Xtreme4, but I had thought
the memory frequency was based on the BCLK?

trents said:
I've read where changing the memory strap can help give more room to tweak with the FSB on the Intel APUs.

trents · Jul 1, 2015

Changing the memory strap and changing the BCLK are not the same thing. When you change the memory strap you are changing the ratio of the memory bus in relation to the BCLK (aka, FSB). Just as a simple and theoretical example if the memory strap is 1:1 and the BCLK is 100 then the speed of PC100 memory would be 100 mhz. The speed of the memory would still be 100 mhz if you change the memory strap to 1:2 and the BCLK to 200. In other words, 1x100 is the same as .5x200. But the impact on CPU frequency would only be half as much if you raise the BCLK by one tick. It would also have a smaller impact on the other buses such as the PCI-e which is not amenable to much change at all, an important issue with the APUs where the PCI-e frequency is in lock step with the BCLK.

Woomack · Jul 2, 2015

On X99 not all memory ratios are working. You have to adjust bclk and memory ratio. x21.33, x22.00, x24.00 are working with bclk 100. Also x26.66, x30 and x32 are working on some OC boards ( like all ASUS ). Most 2666+ memory kits need 125 bclk. At 125 bclk you can use the same memory ratios.
Straps are 100, 125, 167, 200 ... there is no 133 and it won't let you boot on most motherboards without bumping additional voltages etc. At 133 pcie will be too high. Usually it's working +5MHz from each strap so up to 105, 130, 172 ... but not always.

EarthDog · Jul 2, 2015

@magellan... f12 should capture screenshot and put them on a usb stick. Go to your bios and see as there should be a legend to show you what buttons do what in the bios (typically the bottom or bottom right hand corner).

Third try... Did you just try setting the xmp profile with the rest on auto and see if it is stable?

@trents... Intel APU?

trents · Jul 2, 2015

Intel APU: CPUs that have integrated GPUs. At least that's how the term is used in the AMD world. Accelerated Processing Unit.

EarthDog · Jul 2, 2015

That would be nearly every consumer Intel CPU sans s2011(X79/X99) CPUs wouldn't it? Never heard an Intel CPU called an APU before is why I asked.

trents · Jul 2, 2015

Yep, all recent Intel offerings have integrated GPU. Unfortunately, since it pretty much nixes overclocking with the BCLK. I don't know, maybe the term isn't appropriate when applied to Intel CPUs since it doesn't distinguish them from anything else because there isn't anything else on the Intel side anymore.

Woomack · Jul 2, 2015

APU = AMD term because they claim it includes additional features in their integrated graphics like possible additional calculations which are boosting multimedia etc. Intel has no APU, only regular integrated graphics even though there are additional features too.

trents · Jul 2, 2015

Woo, what you're describing sounds the same to me if both have "additonal features" or "additional calculations". In the industry as a whole there is an effort to involve the GPU in a broader range of calculations that have traditionally been handled only by the CPU.

EarthDog · Jul 2, 2015

Intel doesn't make such claims though... they just say we have an integrated GPU. I do not believe it to assist with processor functions like the AMD APU does.

Perhaps this will help: http://www.amd.com/en-us/products/processors/desktop

Key line:

AMD pioneered APUs, combining our Radeon™ graphics and CPU technologies on a single chip. APUs apply graphics resources to processing tasks – so your optimized applications can run faster.

Anyway, we are really sidetracking this guy's thread... let's move on. If you would like to discuss this further, I am happy to split these and make a thread specifically for it.

magellan · Jul 2, 2015

ED, here's the picture of the BIOS settings in question, the DRAM Reference Clock is the setting in question. If I set the DRAM Reference Clock to 100MHz, and attempt to run the memory at anything over 2100MHz the system won't boot, but it will if I set the DRAM Reference Clock to 133MHz.
My overclock now seems stable, and this seems to be the setting that did it for me.
The available settings for DRAM Reference Clock are 100MHz,
133MHz and AUTO. The DRAM frequencies available at a 100MHz vs. a 133MHz setting are also different (as to the speeds).

EarthDog · Jul 2, 2015

Do this...

1. Reset cmos/bios defaults and reboot.
2. Set xmp profile 2. Reboot and confirm it's stable.
3. If not, try xmp profile 1. Reboot and confirm it's stable.
4. Report back.

Also, what memory do you have? Capacity etc? You havent updated your signature and I can only see timings and not capacity. Update your signature so we know what we are dealing with please

magellan · Jul 2, 2015

EarthDog said:
Do this...

1. Reset cmos/bios defaults and reboot.
2. Set xmp profile 2. Reboot and confirm it's stable.
3. If not, try xmp profile 1. Reboot and confirm it's stable.
4. Report back.

Also, what memory do you have? Capacity etc? You havent updated your signature and I can only see timings and not capacity. Update your signature so we know what we are dealing with please

Stability isn't the issue anymore. What I'm really curious is what the DRAM Reference Clock BIOS setting is doing. I'll try your troubleshooting strategy next week, but I have too much remote VPN work to do w/this computer now to monkey around w/BIOS settings ATM.

i7-5820 & Asrock x99 Extreme 4 : memory bus speed affects stability

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