SiRF Atlas-V is a chipset that hosts a GPS RF chip and antenna so you wouldn't necessarily see any SiRF markings or an actual GPS chip. MStarGPS sounds like it could be the brand of your device? Pictures or more info on your device would help.
yea I don't really have much understanding about GPS chipsets, I thought maybe MStarGPS is a chip/receiver that is used in SiRF Atlas-V chipset? I also found out that MStarGPS is the cheapest GPS chip on the market.
Mstar is the chip's brand, ex. Mstar MSB2521 500MHz, as SIRF is a chip's brand, ex. SiRF Atlas-V 600MHz. YF produces boards for GPS devices with eiher MStar or SiRF chip, hence they are named YFMstart and/or YFAtlas.