Corsair Platinum 2666

[Daddyjaxx]

For some reason my Rampage IV BE will not run the 32 GB of memory at 2666. If I set it to XMP, the memory runs at 2666 but it down clocks my CPU from 3400 to 3100. If I set it manually, it won't boot.

It runs just fine at 2400 10-12-12-31. Considering the timings at 2666 are 12-15-15-34, I would guess it actually runs faster at 2400.

Why won't the board run it at te rated speed without down clocking the CPU?

 

[Janus67]

Can you try with 16gb?

 

[Woomack]

It's probably because there are different memory ratios for X79 boards. I would check different BIOS version and if it won't help then set memory manually. For 2666 clock you have to use 125MHz bclk or it won't boot. X79 is supporting memory ratios up to x24, anything above is marked as OC.

There is info on the ASUS site:
"Due to CPU behavior, DDR3 2200/2000/1800 MHz memory module will run at DDR3 2133/1866/1600 MHz frequency as default." so if board sees SPD/XMP profile wrong then can change CPU/memory settings to what it thinks is optimal.

You can probably set 2666-2800 at tighter timings than your memory has but it can take some time to set it optimal as most auto/XMP profiles are usually providing performance settings but in compatibility mode so it run on most available motherboards.

Btw. what product number has your memory and rev. number , I'm just curious what is in these new Dominator Plat.

 

[Daddyjaxx]

Revision 5.29 410470 141204865

Thanks, I'll try the 125 strap.

I was wrong about the stock timing. It is 12-13-13-35.

 

[Daddyjaxx]

I tried setting the strap to 125 with a 28x ratio. The system boots now with the memory at 2666. Won't it be harder to over clock the CPU messing with the BCLK and the multiplier than only the multiplier? I know what the strap is for, so you don't need to explain it to to me. I'm working at 4.5 now running the memory at 2400 and 45x.

 

[Woomack]

On my board all is working fine and I'm not losing stability at 100, 125 or 166MHz. Actually you can set about +7MHz from each strap and it will be probably still stable.
Looking at memory performance scalling on X79 I would leave it at 2666 but try to tighten timings like 11-13-13. Actually raising memory clock above 2400 is not helping much if you have relaxed timings and for Hynix memory it's not so easy to set anything tighter at 2666 ( that's why manufacturers are selling this memory at CL11/12 2666 ).

 

[Ajay57]

The sweet spot for the RIVBE and the X79 Platform is 2133Mhz with tightening timings also 2400Mhz is not to shabby with the speed!

This could help you, and give you some pointers how the Ram the Strap and Bclk work together.

1, http://forums.overclockers.co.uk/showthread.php?t=18476907

I find this a good read being one of the top Overclockers on the HWbot!

Regards,

AJ.

1,

 

[Daddyjaxx]

I've got a lousy 4930K. I can do [email protected] easily. I ran Prime for 12 hours with no issues. When I go to [email protected], I can run 20 runs of Linx with no problem. Prime gives me a 124 BSOD after about half an hour. I upped it to 1.375 and Prime made it about 2 hours before the same BSOD. My 5th core is running 7-15 degrees hotter than my other cores. I'll be in the single digits on some cores, the teens on others, and 23c on core 5 at full load.

I've taken the memory completely out of the equation. I'm running it at 1333.

 

[Woomack]

You have actually quite good 4930K. Most need 1.4-1.45V for 4.6-4.7GHz. My 4930K needs ~1.41V for 4.7GHz. Most 4930K in reviews needed 1.35V for 4.5GHz ( hard to say if it's because of bad chips or user skills ).
You can also compare that these 6 core CPUs are running as hot as 4 core haswell at the same voltage but are clocking higher in average. I really like my 4930k. It could overclock higher but I can live with that as I saw many worse chips.

 

[Ajay57]

I would be very happy with a 4930K @ 4.7 @ 1.35V mine would not OC above 4.5 or more!! But like Woomack said, there is a lot to learn on these Motherboards and how to get the best out of them with the CPU you are using.

Let me say i have had my RIVBE for some time now, and still i am learning new tweaks and settings even today! Why because i have found the Bios settings on this Mobo are set different to your average Board, and this was confirmed by chatting to Raja @ Asus where most of the Info came to light.

If you by chance need any further help, just ask me or Woomack!

Regards,

AJ.

 

[Daddyjaxx]

I set the LLC to Ultra High and that seems to be doing the trick. My CPU is running warmer, with most cores in the high teens and low 20's at full load except that darn 5th core running at 27c. I want at least 5GHz. My evaporator head is still at -38c. That means even the hottest core is outputting 65c of heat.

 

[Woomack]

For 5GHz you may need 1.5V+. I've noticed there are bigger voltage steps once you pass ~4.7GHz. Usually 4.7-4.8 is max on water or good air cooling. To make 5GHz+ you need ss or something better. Max on ss with my chip was ~5.2-5.3GHz ~1.7V while 5GHz was running quite good near 1.5V. Pretty big step in voltage for only 200-300MHz more.

Actually I would stay with water cooling at 4.7GHz than push it to 5GHz on ss. I don't think that additional electricity costs are worth it.

 

[Daddyjaxx]

Already on SS. For day to day, 4.7 @ 1.35 will be fine, but I want at least 5 GHz for benching. With the phase and add my CPU at 100%, that's pulling 750w at the wall. When I crank up the two 780TI's at the same time, it's up to 1350w, and I'm adding two more 780's. That would be 2kw or more.

 

[Woomack]

I was benching 2xGTX780 + [email protected] on 850W Corsair PSU and was fine so I bet you don't need more than ~1350-1500W after OC.

 

[Daddyjaxx]

I agree. The 1350w includes the phase system. I have everything plugged into a Kill-A-Watt. But even with the phase, that's still 800w for the computer. I have two more 780's to add. That's like 500 more watts at full load for the CPU and GPU's. I have the 1200AXi now, soon to be replaced with the 1500AXi.