While the GeForce 8600 GT normally has GDDR3 memory set at 700 MHz, some models, notably from Zotac, are only equipped with DDR2 memory set at 500 MHz. When contacted about this, Nvidia answered that they do not officially support this version of the GeForce 8600 GT. Apparently, they were supposed to be reserved for the OEM market where anything and everything sells as soon as the two parties agree on a price.
Therefore, we should be suspicious of low priced GeForce 8600 GTs, which could offer lower performances. Zotac indicated that its GeForce 8600 GT DDR2 would be sold for 129€ in 256 MB version and for 139€ in its 512 MB version. This is versus 149€ for normal GDDR3 and 256 MB from Zotac.