Despite claims that such a device does not exist, rumours continue to persist that Samsung is readying a higher-end variant of the Samsung Galaxy S5 it just announced at Mobile World Congress in late February. A Samsung device identified as the SM-G906S has surfaced on the GFXBench benchmark websites bearing all the signs that it could be this Samsung Galaxy S5 Prime model.
The benchmark reveals that the Samsung SM-G906S will come with a 2.5GHz quad-core Qualcomm Snapdragon 805 paired with an Adreno 420 GPU, Google Android 4.4.2 KitKat, a 5.2-inch WQHD (2560×1440) display, 3 GB of RAM, 32GB of internal storage (25GB available), a 15MP rear camera (more likely a 16MP one), 2MP front-camera, GPS, Wi-Fi, Bluetooth and a range of sensors including a barometer.
In early February, the SM-G900R4 popped up in AnTuTu benchmarks. It was very similar to the SM-G906S except that it sported an older Snapdragon 801. An older GFXBench entry for the SM-G900S also paints a similar picture. It may well be that Samsung was running prototypes of this upcoming device with the older processor while it waited for Qualcomm to provide it with Snapdragon 805 SoCs. Now that it has them, the updated device may well have gotten a new model number to differentiate it from older prototypes.
Keep in mind that there is nothing that explicitly suggests that the SM-G906S will be a Samsung Galaxy S5 variant. It could well launch as a different device such as the Galaxy F (Project F?) that has also been rumoured. While the name of the device is conjecture, it does appear that the device itself is not though.
Sources : GFXBench // PhoneArena