I have a Dell Inspiron 530, which apparently has a very locked-down BIOS. From what I can gather, my motherboard is set at 1.8V for RAM (PC2-6400). What would happen if I were to buy RAM rated at 1.9V? Would it be better to buy 5-5-5-12 1.8V RAM, or 4-4-4-12 1.9V RAM, taking into consideration that I can only put out 1.8V?

Also, I currently have 3GB of stock Dell RAM. Before I even consider upgrading the RAM, I have to wonder if I even need to. I'll be doing a lot of gaming and everyday multitasking, and I just want this computer to be as fast as it can possibly go. As of right now, I have 2x1GB and 2x512MB PC2-6400 sticks (made by Hyundai and Qimonda?!), with 6-6-6-18 timings and 2T command rate, as measured by CPU-Z. If I were to upgrade to 4GB of whatever RAM works best in the first paragraph above (3.25GB since I have 32-bit Windows Vista), would I be able to expect any significant performance increase?

Thank you for your help!

You'll see a difference depending on what programs you use. Vista prefers more RAM for superfetch though and makes application starts real speedy.
Can you change RAM voltage? If you can, you could get 1.9v RAM but you'll see almost no performance increase, getting the cheapest would be the best bet. Wat chipset/mobo does your Dell use?

If you have 3 Gb running currently, there is no need to upgrade the RAM. The BIOS has no adjustments as to FSB or RAM frequency correct. So any RAM you put in the system will default according to BIOS. If you were using a 64 bit OS, maybe 4 gigs, but still 3 gigs is enough. If you are just looking to buy new RAM try using a memory advisory tool like this. Enter you system and the company guarantees the RAM to work. You are limited as to what DIMMS will work in the system due to having no BIOS control over the settings, especially so with no voltage increase available.

http://crucial.com/

Okay, I'll just leave it alone and stay with my stock RAM.

I'm still curious about the voltage issue, though. If I were unable to get anything higher than 1.8V out of my motherboard due to it being locked down by Dell, what would happen if I installed RAM that requires 1.9V-2.5V? Would it just not work, or would it just run very slowly?

If you can borrow a single DIMM of RAM requiring higher vltage than 1.8v, try it. RAM manufacturers suggest the voltage needed to run at the timings and speed they advertise. I have micro boards that have little or no voltage adjustment. Most of those are 'picky' about the RAM that will run.

Your system would not run 'slowly' if you used noncompatable RAM. It would not run at all, lock up or blue screen and crash constantly. If you have 3 gigs of RAM running stable in that system, best to leave it alone and enjoy it.