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Ram frequency affects rift tracking.

UnFknBLievable
Expert Protege
i have a high end system running perfectly fine, stable and fast (i7 6700k @ 4.6ghz, gskill 3000mhz ddr4, GTX1080, win 10 and Asus z170-AR motherboard.

only adjusting the memory frequency between default factory speed (3000mhz) and underclocking it down to 2144mhz, why does the tracking system of the rift go from being unstable and often unplayable to flawless?

oculus can you look into this please? 
58 REPLIES 58

elboffor
Consultant


I have just done some more testing.
XMP timing enabled, ram FREQUENCY is the only variable.
2133mhz - stable, flawless.
2400mhz - stable, flawless.
2700mhz - noticeable jittering but tracking was fine.
3000mhz - bad tracking, errors, warping, ect.

Can someone from oculus please give some kind of explaination? My system is 100% stable and as Flexy123 suggested, I ran Aida64 with no issues, errors or loss of performance at full factory clock speed (3000mhz). Timing is not the problem, the Frequency is affecting my tracking.


Your problem may well be timing actually. The timings generally go down as the frequency goes up.

It has always been the case in my experience.

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There are many others like it, but this is mine.

flexy123
Superstar


VRoaaar said:

Run OCCT with every RAM frequency to see if your system is really stable or not. Run each test at least 30 minutes or more. See here.

Yes I asked him that..he didn't directly answer it but I assumed he did. (He pretty confidently said his system is stable).I also would be interested to know whether he can run 30-60min  OCCT on "large" without problems. The thing is, XMP memory settings are usually not exactly hardcore overclocking settings, they are normally rather conservative.

TBH...for me it's very difficult to see how changed ram timings WHILE THE SYSTEM REALLY BEING STABLE (ie: tested with OCCT, memtest etc.) would cause such problems. The only explanation for me would be if another clock in the BIOS would be off, like PCI bus freq or something like this....or (far fetched...) that his motherboard bios does something odd it shouldn't do when changing memory speed. I am still blindly guessing his system is in reality not stable.

He needs to run OCCT at the bare minimum, and preferably also memtest (the Windows version), and spawn several instances of it and then have it run for some hours to really test. I am saying this since OOCCT/large..while being very good..doesn't test ALL memory...and the memtest that you can from CD/boot isn't as sensitive as the memtest tool that runs in Windows.

flexy123
Superstar
Uhm..you didn't say what type/brand of ram it is...you only listed the board specs and what ram it supports. Would be interested what memory you have in there.

elboffor
Consultant
I smell cheap ram...
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There are many others like it, but this is mine.

edmg
Trustee


TBH...for me it's very difficult to see how changed ram timings WHILE THE SYSTEM REALLY BEING STABLE (ie: tested with OCCT, memtest etc.) would cause such problems.



The Rift software is looking for flashing lights in images. The camera is doing repeated DMA, many times a second, to big blocks of RAM through the CPU's memory controller, which is only rated to 2133MHz. May not take many memory errors to confuse the software about which pixels are flashing and which aren't.

And, oddly enough, it works fine at the frequency the CPU is rated for.

Ernimus_Prime
Heroic Explorer
My PC is running with 16 gigs DDR4-3000 ram and have no problems. 
ASUS TUF GAMING X570-PLUS (WI-FI), Ryzen 7 3700x, 16 gigs ram DDR-4 3600 MHZ. SSD XPG 8200 pro 1 TB. WD Black 4 TB. Windows 10 PRO 64-bit. MSI VENTUS 3 RTX 3080 OC, Primary: MSI MAG274QRF-QD 2nd monitor: Acer Predator XG270HU 1440p@144 hz, Phanteks Enthoo Pro case. Corsair rm750x PSU. Rift S.

edmg
Trustee
It's going to depend on a lot of things, like the precise CPU and memory you have (not just the model, but the characteristics of the specific chunk of silicon it's made from), the timings they're using, and the motherboard layout.

But it is making me wonder whether I should switch mine back to default memory timings from the XMP ones it's currently using.

RedRizla
Honored Visionary
Update your Bios to F21, I have a Z170 motherboard and it's been piss poor until the latest Bios. It has had voltage problems all the way up to Bios version F21. Now my problems have gone but I'll continue to check.

UnFknBLievable
Expert Protege

flexy123 said:

Uhm..you didn't say what type/brand of ram it is...you only listed the board specs and what ram it supports. Would be interested what memory you have in there.


G.Skill DDR4 3000mhz Ripjaw X F43000C15-8GVR.


lovethis said:

Update your Bios to F21, I have a Z170 motherboard and it's been piss poor until the latest Bios. It has had voltage problems all the way up to Bios version F21. Now my problems have gone but I'll continue to check.


Already Running the latest BIOS (v.3301) This BIOS version has also solved other issues I had with previous BIOS revisions.


edmg said:



TBH...for me it's very difficult to see how changed ram timings WHILE THE SYSTEM REALLY BEING STABLE (ie: tested with OCCT, memtest etc.) would cause such problems.



The Rift software is looking for flashing lights in images. The camera is doing repeated DMA, many times a second, to big blocks of RAM through the CPU's memory controller, which is only rated to 2133MHz. May not take many memory errors to confuse the software about which pixels are flashing and which aren't.

And, oddly enough, it works fine at the frequency the CPU is rated for.


Thank you for the only decent theory as to what could be going on.

I don't know how many times I have repeated myself on multiple posts. If my system was "unstable", I'd be having other symptons with software and I wouldn't be here trying to fix it.

Memory is currently at 2400mhz manually set.
XMP profile timing from CPU-Z
Freq - 1500Mhz
CAS - 15
RAS to CAS - 15
RAS Precharge - 15
tRAS - 35
tRC - 50
Voltage - 1.35v

I have downloaded OCCT, ran it for 30min at factory 3000mhz XMP profile. (it's late) and was fine

UnFknBLievable
Expert Protege

flexy123 said:

Uhm..you didn't say what type/brand of ram it is...you only listed the board specs and what ram it supports. Would be interested what memory you have in there.


G.Skill DDR4 3000mhz Ripjaw X F43000C15-8GVR.


lovethis said:

Update your Bios to F21, I have a Z170 motherboard and it's been piss poor until the latest Bios. It has had voltage problems all the way up to Bios version F21. Now my problems have gone but I'll continue to check.


Already Running the latest BIOS (v.3301) This BIOS version has also solved other issues I had with previous BIOS revisions.


edmg said:



TBH...for me it's very difficult to see how changed ram timings WHILE THE SYSTEM REALLY BEING STABLE (ie: tested with OCCT, memtest etc.) would cause such problems.



The Rift software is looking for flashing lights in images. The camera is doing repeated DMA, many times a second, to big blocks of RAM through the CPU's memory controller, which is only rated to 2133MHz. May not take many memory errors to confuse the software about which pixels are flashing and which aren't.

And, oddly enough, it works fine at the frequency the CPU is rated for.


Thank you for the only decent theory as to what could be going on.

I don't know how many times I have repeated myself on multiple posts. If my system was "unstable", I'd be having other symptons with software and I wouldn't be here trying to fix it.

Memory is currently at 2400mhz manually set.
XMP profile timing from CPU-Z
Freq - 1500Mhz
CAS - 15
RAS to CAS - 15
RAS Precharge - 15
tRAS - 35
tRC - 50
Voltage - 1.35v

I have downloaded OCCT, ran it for 30min at factory 3000mhz XMP profile. (it's late) and was fine