Qualified Vendor Lists, or QVL for short, are probably familiar to anyone who has looked for a suitable pairing of motherboard and RAM kit. Since RAM kits with an XMP profile are not covered by the official specifications of the CPU manufacturers (Intel or AMD), motherboard and RAM manufacturers test the compatibility between their products themselves to give the end user security when buying – at least that is the theory. The fact that reality often looks different is nothing new in enthusiast circles, but that doesn’t make it any less annoying for part-time PC builders.
Forum member Ro77b had contacted us about just such a case. Two RAM kits from different manufacturers, both listed as “XMP compatible” on his motherboard’s QVL, simply wouldn’t run as specified. The affected Gigabyte Z690 Gaming X (DDR5) was even sent in to Gigabyte support in the meantime and an RMA was performed. But even with the replaced motherboard and the latest BIOS, there was no compatibility to be found. The despair is understandable when the new, supposedly compatible, and not exactly cheap PC parts still don’t work with each other as they should, after months of troubleshooting.
So much for the premise of today’s piece. Thankfully, Ro77b sent us the motherboard so that we could see the situation for ourselves and double-check it with our various RAM kits and CPUs. I also want to preface this by saying that we are not here to “bash” any one manufacturer or look for someone to blame. Instead, the aim is to shed light on the various interpretations of “QVL” in the hope that this may trigger improvements for the future, but more on that in a moment. First of all, the actual problem:
Gigabyte Z690 Gaming X as an example
It is no surprise that the motherboard with 4 DIMM slots and no Qcode display will not achieve top performance in RAM overclocking – because that is what XMP ultimately is. The expectation should be, you buy a RAM kit officially listed as compatible, plug it into the primary slots A2 and B2, enable XMP and you’re happy.
However, if you try this now with one of the faster listed kits like ADATA’s AX5U6000C4016G-DCLARBK, which we already had in our dedicated review, the motherboard simply doesn’t boot anymore. To be precise, the board tries to train the RAM 10 times in a row with the settings specified in the XMP profile – recognizable by the alternate lighting of the debug LEDs of CPU and RAM – and then goes into recovery mode, where it asks to adjust the settings.
However, the QVL on the Gigabyte website claims that exactly this should work. The table even differentiates between the configuration of 1, 2 and 4 slots and the operation by activating the XMP profile, so you could think that two modules should work in the XMP “Plug and Play” mode. What does Gigabyte support say about this and what exactly does the “v” in the QVL mean?
The “v” therefore describes that exactly the kits with the exact product number were tested with the mainboard in the corresponding configuration. In return, however, it is also said that even if a kit is tested, it is not guaranteed that it actually works in XMP. I couldn’t believe the latter at first, so I asked again critically:
Thus, “production variances” in CPUs would be the cause that not every system with a motherboard and tested RAM kit can operate in XMP. There is actually some truth to that, as we could find out ourselves in our articles about binning Alder Lake CPUs. Some CPUs of the same model only managed to boot DDR5-7250 on our 2-DIMM Maximus Z690 Apex boards, while another identical CPU from the same tray reached 7650 Mbps.
So, I grabbed the CPU with the best DDR5 IMC (Integrated Memory Controller) out of 60 tested and packed it into the Gigabyte Gaming X. Surely, such a highly selected CPU must then manage to at least keep up with the QVL! But unfortunately no, and also my various other Alder Lake chips, i5, i3 and Pentium all fail the 6000 Mbps XMP profile of the ADATA modules, just as Ro77b had reported.
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