It does not matter which drive is set to which. As long as one is set to Master, and the other is set to Slave, OR BOTH are set to cable select.

When cable select jumpers are configured, the master will be the first connector from the mainboard, and the slave will be the end connector (I think lol) ... or its the other way round

Also, im not sure you quite understood what i was getting at with:
Not sure if this has been asked or not, but what is the RAM access speed in the bios settings?

It may be a problem with the RAM or the bus causing a slow read which results in slow data transfer (burn)