memory slot

Hi folks, I have a 10yr old PC that works just fine with Windows 7. The problem is, I also run Pro Tools 10, which was fine when the motherboard was working to full capacity, ie 8GB RAM (2x 4GB max. memory slots). However, now, the PC system only works with one memory slot filled, ie 4GB RAM...

Yesterday i bought a desktop, windows 8, it was running amazingly fast, everything is so smooth, an multitasking is great, so i downloaded couple of programmes, that i need,( updated my graphics drive / skype / downloaded Synapse for my Razer keyboard ) after that, i download kaspersky internet...