Win 7 slowing down on fast system

I have 7 Ultimate on a quadcore i750 (at 2.7 clock rate), asus p755d mb, with four WD enterprise class 1tb drives in raid 10 configuration (using Intel Matrix Manager), 4gb Corsair memory (that passes Memtest). Data transfer rates were originally 244MBs per second and boot times very fast. Disks seem to be defragged OK and when Windows 7 hangs (frequently) Matrix Manager works as advertised and rebuilds the array OK. Now data transfer rates are quite slow (for 64kb sector size reformatted USB) down to under 1MBs and booting takes several minutes. The only system problem I am aware of is that the start bar / Computer / Manage is sometimes non-functional but will suddenly become functional. I run Bitdefender, SuperAbtiSpyware, Malwarebytes, HiMan Pro, and Hijack weekly and have no apparent viruses. I also run a rootkit finder monthly and again no obvious infections. Any ideas or is just Win 7 deteriorating (installed Nov 2009). John

We see a lot of problems with Win7 on RAID arrays. If it's intended to boost performance you can see the results, and if there is no real redundancy what is the point with built-in Drive Imaging?

The best performance boost you can get is an SSD, and a clean reinstall using these tips to get a purrfect install: re-install windows 7

My guess is either the HD or memory. Try taking a stick of memory out and see how you get on. My computer use to hang occasionally when I used RAID 0, then my hard drive died. In theory, by using RAID 0 you have a greater risk of losing data - if either disk goes, you loose all data. Really what you want RAID 5 in my opinion.

The raid array is raid 10 (i.e. raid 0 plus raid 1)and although the performance boost was good (at the time passmark showed only 2 SSD systems providing better than 244MBytes ps) I installed it because of the rebuild capability. I work in digital security and I was fed up with having to repair/reinstall or get zapped by windows one way or another.

The disks check out OK but I will run another memory test as it was not top of the line memory.

Thanks for the suggestions.

RAM - Test with Memtest86+

Best overnight to stress test.