In computer memory systems, Chipkill is IBM's trademark for a form of advanced Error Checking and Correcting (ECC) computer memory technology that protects computer memory systems from any single memory chip failure as well as multi-bit errors from any portion of a single memory chip. It performs this function by scattering the bits of an ECC word across multiple memory chips, such that the failure of any one memory chip will affect only one ECC bit. This allows memory contents to be reconstructed despite the complete failure of one chip. The equivalent system from Sun Microsystems is called Extended ECC. The equivalent system from HP is called Chipspare.
Chipkill is frequently combined with dynamic bit-steering, so that if a chip fails (or has exceeded a threshold of bit errors), another, spare, memory chip is used to replace the failed chip. The concept is similar to that of RAID, which protects against disk failure, except that now the concept is applied to individual memory chips. The technology was developed by the IBM Corporation in the early and middle 1990s. An important RAS feature, Chipkill technology is deployed primarily on SSDs, mainframes and midrange Unix or Linux servers.
I looked up in IBM doc's and the answer is (referfing to: IBM SystemX x3655 sales guide):
If Chipkill-enabled and non-Chipkill memory is used in the same system, Chipkill protection is disabled for all DIMMs.