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ASUS P8B75-V XMP not working

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crisorlandobr

Registered
Joined
Mar 4, 2017
Hello

I have an ASUS P8B75-V with an i7-3770k

I got 4 GSKILL TridentX 8GB 2666Mhz and the mobo can only run them on 1600Mhz (and the default even with XMP is 1333Mhz)

When I set XMP to 2666Mhz or even anything more than 1600Mhz it does not boot and I have to press MemOk button to reset the RAM settings and it goes back to 1333Mhz

The mobo spec says it can (or should) accept even 2800Mhz RAM but it does not

Is there a way to really run this RAM at full speedy (or even at 2200 or 2400 at least) with this mobo ?

In XMP settings I set the DRAM voltage to 1.65v to see if it could run, but even so it does not.

Tks
 

trents

Senior Member
Joined
Dec 27, 2008
Please attach a pic of CPU-z tabs: "Memory" and "SPD". Crop and save the images with Windows Snipping Tool and then attach them using the Go Advanced button found at the lower right corner of any new post window. It's possible the bios is assigning wrong timings in XMP mode and you may need to manually set them. The "Memory" tab in CPU-z will show what you are currently running at and the SPD tab will show what the manufacturer recommends.

Another question: Are you running two sticks of RAM that were bought as one dual channel kit or were the two sticks bought at different times? And have you tried running just one stick in each of the RAM slots on the board using each RAM stick one at a time?
 
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crisorlandobr

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Mar 4, 2017
Hi
Actually CPUZ was reading it as 800Mhz (when set to 1600Mhz)
I know that DDR3 shows "half" of the real frequency but that is not the case

Here are the CPUZ print screens

Tks
cpuz1.jpg cpuz2.jpg
 
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crisorlandobr

Registered
Joined
Mar 4, 2017
Please attach a pic of CPU-z tabs: "Memory" and "SPD". Crop and save the images with Windows Snipping Tool and then attach them using the Go Advanced button found at the lower right corner of any new post window. It's possible the bios is assigning wrong timings in XMP mode and you may need to manually set them. The "Memory" tab in CPU-z will show what you are currently running at and the SPD tab will show what the manufacturer recommends.

Another question: Are you running two sticks of RAM that were bought as one dual channel kit or were the two sticks bought at different times? And have you tried running just one stick in each of the RAM slots on the board using each RAM stick one at a time?


Hi
I upped the CPUZ screen

And it was 2 16GB (2x8) Kits

Tks
 
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crisorlandobr

Registered
Joined
Mar 4, 2017
Hi

Above I uploaded the screenshot of SPD settings and XMP is there too

But when I try to set the frequency to 2666 (or even 2400 or 2200) inside the BIOS it does not boot

tks
 
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crisorlandobr

Registered
Joined
Mar 4, 2017
Yes
It shows XMP tab, but in the BIOS when I set XMP to 2666 it does not boot
It only boots when I set to 1333 or 1600, and in Auto mode when it only gets to 1333

ps: if XMP is showing 2666Mhz in CPUZ it means it is working ? because the other memory tabs are only going on 1333 or 1600

Tks
 

trents

Senior Member
Joined
Dec 27, 2008
Something is wrong with this number. It looks like you are trying to overclock with the BCLK.
 

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crisorlandobr

Registered
Joined
Mar 4, 2017
Actually not
When i set it to 1600Mhz it works as it shows DRAM freq as 800Mhz

But when I set to 2666 it does not

Now the machine is in XMP auto (with no BCLK) and its working on 1333Mhz (667)

XMP shows, but I don´t know if it is actually working as 2666Mhz since when I set it to that frequency, it does not boot

Tks
 

trents

Senior Member
Joined
Dec 27, 2008
So I'm wondering if somehow when you set the RAM frequency to 2666 XMP the bios is also jacking up the BCLK and that's why it won't boot. What frequency is the RAM set to in the CPU-z pics from post #4. That picture from the CPU-z memory tab shows an odd frequency that does not correlate to any standard JEDEC frequency. 2x823 is 1646 mhz in DDR terms.
 
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crisorlandobr

Registered
Joined
Mar 4, 2017
Hi

Actually when I setted the RAM to 2666Mhz it did not change BCLK, it just did not boot at all, since I did not change anything there and it was at default (100)

And now with the auto-settings in XMP CPU-Z shows 1333 (667) ate JEDEC
cpuz3.jpg
Tks
 

trents

Senior Member
Joined
Dec 27, 2008
You misunderstand what I'm getting at. If setting the RAM frequency to XMP-2666 did in fact increase the BClk it would cause the computer not to be able to boot because raising the BCLK would also cause the RAM frequency to rise above 2666 mhz where it would not be stable and cause boot failure. You may not be aware of this but RAM frequency is tied to the BCLK. It would only be 2666 at a BClk of 100 mhz. If the BCLK is increased the RAM will no longer be at 2600 mhz but would be faster.

I'm beginning to think your bios' memory divider is messed up.
 
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crisorlandobr

Registered
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Mar 4, 2017
Actually it dit not increase BCLK, since it was at default number (100) and even so it did not boot at 2666Mhz
I will try (again) cleaning the CMOS, or even taking the CMOS battery off to see if it works, and I will reply here later

Tks