Well no 2 programs will ever be 100% accurate at proving stability - but Prime95 and LinX combined are a damn good start.
To start, a LinX run with at least 50% of your RAM for an hour should get you a baseline of stability. After you pass that, run Prime95 small FFTs for 4-8 hours (your preference, but I usually run 8 hours). If you can pass both of those tests you're on your way to having a stable system. I've yet to put a system together that could pass those two tests combined and move on to fail something else.
Z68XP-UD4 | 2700K @ 4.7 GHz | 16 GB | GTX 780 SLI | PCP&C Silencer 950 | XSPC RX360 | Heatkiller R3 | D5 + RP-452X2 | Cosmos II | 480 + 240 + 128x4 SSDs