NVIDIA quietly launched the GeForce MX150 mobile GPU in May of last year. The team at Notebookcheck discovered that there are actually two variants of the GeForce MX150 in the wild - the standard 1D10 variant and the much slower 1D12 variant. Normally, this wouldn't raise any alarms. However, neither NVIDIA or the manufacturer distinguish the two variants from each other. Buyers who purchase an ultrabook or notebook with a GeForce MX150 are basically playing the lottery. They have no idea which variant is inside the product until they run an utility like GPU-Z to find out. But just how significant is the performance difference between the two variants? Let's look at Notebookcheck's findings.Starting with the GeForce MX150's specifications, the standard 1D10 variant has a 1469 MHz core clock, 1532 MHz boost clock, and 1502 MHz memory clock. Notebookcheck first saw this variant in the MSI PL62 and Asus Zenbook UX430UN. They later discovered the underclocked 1D12 variant in the Lenovo IdeaPad 320S, ZenBook 13 UX331UN, Xiaomi Mi Notebook Air 13.3, HP Envy 13, and ZenBook UX331UA notebooks. The 1D12 variant has a 937 MHz core clock, 1038 MHz boost clock, and 1253 MHZ memory clock. Right off the bat, that's a 36 percent reduction in the core clock alone. According to the 3DMark and 3DMark 11 tests, consumers can expect anywhere from a 20 to 25 percent performance hit with the less powerful variant. The charts don't lie. Of the 13 notebooks tested by Notebookcheck, the five models equipped with the 1D12 variant of the GeForce MX150 are at the bottom of the list. Nvidia's move to sneak the 1D12 variant into thin and light notebooks was probably to meet the 10W TDP envelope as opposed to the original variant's 25W. Luckily, the 1D12 variant has only appeared in 13-inch notebooks.