X399 Phantom Gaming 6 + Corsair RAM = Only 50% Fun
Printed From: ASRock.com
Category: Technical Support
Forum Name: AMD Motherboards
Forum Description: Question about ASRock AMD motherboards
URL: https://forum.asrock.com/forum_posts.asp?TID=18799
Printed Date: 09 Aug 2025 at 12:47am
Software Version: Web Wiz Forums 12.04 - http://www.webwizforums.com
Topic: X399 Phantom Gaming 6 + Corsair RAM = Only 50% Fun
Posted By: Troy
Subject: X399 Phantom Gaming 6 + Corsair RAM = Only 50% Fun
Date Posted: 09 May 2021 at 6:08pm
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Hi there, I have a problem with my X399 Phantom Gaming 6 Motherboard. I have installed 4 bars of Corsair Vengeance Pro with 16GB (2x8GB) each. Their SKU is CMW64GX4M4E3200C16. My CPU is a Threadripper 2920x. I did a CMOS reset and loaded the UEFI defaults afterwards. The RAM bars are placed in the recommended slots A2, B2, C2 and D2. They are all recognized in BIOS/UEFI, but only with half of their memory size (8192MB each) and a clock speed of 2133MHz instead of 3200MHz. While I can set the XMP 2.0 profile 1 in order to adjust their speed to 3200MHz, I cannot make the board detect the correct memory size of 16GB each, so 64GB in total. What could I try to fix this? Thanks guys, I am a pretty desperate noob and want to excuse myself in case this is a well-known problem to experts. |
Replies:
Posted By: Troy
Date Posted: 09 May 2021 at 6:13pm
| Update: My BIOS/UEFI Version is 1.31 (latest) |
Posted By: Troy
Date Posted: 10 May 2021 at 1:08pm
| Thread can be closed. Turned out that I was misled by the labels on the memory bars. They show the size of the KIT, not the size of the bar. |
Posted By: Xaltar
Date Posted: 10 May 2021 at 5:10pm
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I was about to say are you sure they are 16gb modules :) I am glad you are all sorted. I have the same board paired with a 2950x, 2 years in and it's still running flawlessly. Enjoy :) ------------- 
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Posted By: Troy
Date Posted: 10 May 2021 at 5:14pm
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Hi Xaltar, thanks for your answer. While I now know the correct size, I noticed some issues with the speed and have it now set to 2666MHz. Do you have the RAM running at 3200 MHz? I experienced some BSODs with this speed and with 3000 MHz. Anything board specific I have to set up? Do I need the DRAM calculator trickery? |
Posted By: Xaltar
Date Posted: 11 May 2021 at 3:16am
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You will likely need to use DRAM calc. I got lucky with mine, my RAM is Samsung B-Die based so it worked right out of the box @3600 once I enabled XMP. Several other kits I have tried did not work with XMP though and required manual settings using DRAM Calc. -------------
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