8GB ram plenty for running Logic 9?

Question

After dealing with my computer only booting in safe mode, getting new ram and finding out that the problem was my graphics card, I upgraded my Mac Pro 1.1 with the ATI 5770. (OS is Lion 10.7.5) In the process I ended up buying 4 times 2GB ram. I still have 2time 1GB that work fine. Should I stick to only using the new ram (8GB) or is there any point in keeping my old 2 GB and running 10GB. I use the computer mainly for running Logic 9. It was getting slow and kept getting stuck here and there with my previous 4GB. I work on commercials at times and link video but don't actually do any video editing.
Thanks for any suggestions.
Very happy with my new graphics card, btw..thanks to Hatter!
Matt

Answer 1

Use the new RAM. The stuff from Amazon is nice and using all the same set IS best policy.
New on A1:2 and whatever else in B1:2
4 or 8 DIMMs is what you want to use. There is small higher latency using 6 or 8.
For best performance on Mac Pro, install memory in risers symmetrically
The Mac Pro comes with two memory riser cards, each with four DIMM slots. With a total of eight slots, you can add up to 16 GB of memory.
Note: DIMMs must be installed in pairs of equal size from the same vendor. For instance, you must not have one or three DIMMs on either riser at any time. Additionally, two DIMMs from different vendors should not be combined and used as a pair.
Other configurations of DIMM pairs are still compatible with Final Cut Studio, but may not achieve the same performance levels as when DIMM pairs are installed on both risers evenly.
Riser A contains:
Riser B contains:
2 x 512MB
2 x 512MB
2 x 1GB
2 x 1GB
2 x 2GB
2 x 2GB
4 x 512MB
4 x 512MB
4 x 1GB
4 x 1GB
4 x 2GB
4 x 2GB
https://support.apple.com/kb/TS1957