The efficiency of two approximate Hartree-Fock approaches was benchmarked. Weigend's RI-JK algorithm is compared to the recently developed RIJCOSX technique in terms of accuracy and total wall clock times. Both methods reproduce the canonical results within the chemical accuracy of similar to kcal mol(-1). RI-JK turns out to be more robust than RIJCOSX due to an overall positive error in the total energies. However, RIJCOSX outperforms RI-JK regarding speed-ups for the largest (gly)(8) chain and maintains comparable accuracy. (C) 2009 Elsevier B.V. All rights reserved.