Windows 7: Computer only wakes from Sleep half the time

This has been an ongoing issue with my computer only waking from sleep half the time. The other half I need to actually power cycle my machine in order for it to wake. I know when it is going to wake properly because I hear the DAC on my Asus Xonar Essence STX Sound Card click on and if it's not going to work obviously I don't hear the click.

I have tried the following:

- Complete system rebuild with new hard drives, reinstall of windows
- All drivers updated and bios updated (I have been through a fair few driver updates because this has been an issue for over a year)
- New Memory installed
- Played with as many power settings in the bios as possible

I am really starting to think it is a hardware issue with either my motherboard or video card but don't have a spare of each of these and don't want to buy new stuff just to test it.



Here are my Specs:

Motherboard: Asus P8Z68-V Pro
CPU: Intel i7 2600
Video Card: Gigabyte 6950 (in eyefinity with 3 Monitors)
Sound Card: Asus Xonar Essence STX
HDD: 2 x 240GB Sandisk Extreme SSD (Raid0)
Memory: Kingston Hyper X 4x4GB (16GB Total)
PSU: Seasonic X Series 750w
Monitors: Samsung MD230x3 (3x23") 2 connected via DVI and 1 via DisplayPort

As mentioned the hard drives and memory were replaced so it can't be either of those. Also it can't be any settings because it does wake via my keyboard/mouse half the time. It is also hard to troubleshoot as it may work 3 times ok and even wake form sleep overnight but then I could leave it for 30 mins come back and it won't wake that time, there is no pattern that I can make out, not sure what else I can do to troubleshoot this but it is really annoying as my computer gets a lot of use and would rather put it to sleep than continually turn it off and on.

Thanks in advance.

Do you have any programs running when you put it to sleep?

Yes I usually just leave all my program running when it goes to sleep Firefox, Outlook, Skype, dropbox, sugrasync, metabrowser, RDP connections etc

sleep seems to be a buggy concept, I constantly see driver updates, bios updates etc. that fix sleep issue so seems its a tough issue for hardware vendors.

One thing I would try is disabling things like WOL on your lan card. Also check in device manager allow this device to sleep settings for all your bits of hardware.