Why are only the primary RAM slots available i7-2620

Hi, I'm a newbie here and I just purchased a Dell Precision M4600, 8 GB memory running Windows 7 pro 64 bit and the Quadro 2000M. The only change I'd like to make is to add another 8 GB memory to the secondary RAM slots but only the primary RAM slots are available for the i7-2620 and other dual cores and both the primary and secondary RAM slots are available to the quad and extreme processors? I refused to pay Dell's outlandish price for the 2X8 RAM. I am running AutoDesk overlying applications and the laptop is not nearly as fast as my old M4400, running the same apps, with the T9900 chip with 8 GB memory running Windows XP Pro 64 bit and the Quadro 1700M. I spoke with my AutoDesk rep who said the laptop should work but may need more memory. I read in the mobile processor comparison that the i7-2620 is much faster than the T9900 before I purchased. I have spoken with Dell techs who say that it is in the architecture of the mother board vs the BIOS but can't tell me why. I have added a Crucial M4 256 SSD which helps with all but the AutoDesk apps. Could a BIOS mod help this?
Thanks

 

First off, you need to see how much memory you are acutally using. crt-alt-delete - task manager, performance. Or run the cpu meter gadget. I really doubt memory is your problem, especially if the M4400 with 8GB is faster. Windows XP does use less memory and doesn't have as much crap running for the system though.

The 2000M is a much better card so thats not the problem. The CPU should not be the problem either. I know that AutoCad only uses 1 core from the processor; so having a dual core is better then a quad core. Hence the mhz being split up. Not sure how the 4 threads works with the new i's.

Make sure there is not other programs running, like windows update, essentials, etc. I know when I do a fresh install of windows 7, it is very sneaky and likes to update without you knowing, you go to reboot and it says its updating the system LOL... I Just then turn the auto updates off. Get rid of norton antivirus if you are running that. Run MS security essentials, its much better and free.

Make sure you have all the latest updated drivers for the M4600 and bios. I bought my M6600 and it had bios A02, and I had to update all the way to A12 lol!!!

 

^Windows NEVER auto updates without telling you on a fresh install (the exception being a custom install that has this already set such as a corporate IT image). You have to actually tell it during the setup how you want your system updated. It will also ask you this again when you update to the newest version of Windows update. (Again, corporate IT policy may override this behavior)

As for autocad it will use multiple cores only for very specific tasks, you can get the details here

Autodesk - AutoCAD Services & Support - Support for multi-core processors with AutoCAD

It will also use as much ram as it can from the system so if you are doing intensive work with large complicated images, you need more ram to prevent disk thrashing.

According to Dell, you can install up to 32GB in the system (4 8GB dimms) but the speed will be reduced to 1333Mhz vs 1600Mhz. All of those processors use the same memory controller but if those are sandy bridge cpu's some have a 16GB limitation (i7 2640 for example). You can visit Intel.com and look up the max memory for each CPU

 

The situation is quite simple, if unfortunate.

Intel has decided that dual core processors can only work with 2 RAM slots. You need a quad core to support all 4. Thus your laptop with a quad core CPU would allow you to fill all four slots, but with a dual core you can only use two.

It's not nice, but it's another way Intel makes you pay for a better CPU!