Renewing cluster hardware

After almost nine years, the hardware from the old norma cluster (circa 2009) is useless for all practical purposes. Have been thinking about the possibility of preserving its (still) functional part and only upgrade the GPUs. Given that the CPUs are weak (Q6600 Kentsfield 2.4 GHz quad processors) I thought I could try with a cheap GPU and see how it goes. Adding a GTX1070 wouldn't make sense, so the first attempt was a GTX1050. The golden standard for comparing the performance is scarlet (i7-6800K@3.4GHz + GTX-1070). The findings were not surprising (system with 9418 atoms and a 4 fs/step using HMR) :

• Scarlet (i7-6800K @ 3.4GHz + GTX-1070)                 ==>  445 ns/day
• Old AMD FX-8150, 8 cores @ 3.6 GHz + GTX 1050  ==>  195 ns/day
• Old Q6600 @ 2.4GHz box + GTX 1050                      ==>  135 ns/day

Given the current price of a GTX1050 (~190 €) would it may make sense to order a handful of 1050s ? An additional test is to replace the boxes altogether with 8 core AMDs. Have ordered a relatively inexpensive box containing an AMD FX 8350 @ 4 GHz + a GTX 1050. The results were consistent with cost : at approximately a third of the price, you get half the performance (225 ns/day for a 9500 atom system on the new box, versus 445 ns/day on the i7+GTX-1070 box).