Hi,

I was wondering if someone can advise me on the best ram to purchase. I have just recently bought the Dell XPS 420 as there was a special promotion. The current system specs are:

Intel® Core 2 Quad-Core Processor Q6600 (2.40GHz, 8MB, 1066MHz)
3072MB 667MHz Dual Channel DDR2 SDRAM [2x1024/2x512]
SINGLE 512MB NVIDIA GeForce 8800GT card
640GB Dual Hard Drive Raid 0 Stripe (2x320GB - 7200rpm)
Genuine Windows Vista Home Premium - English

Now I am looking to unisntall Vista Home and replace it with Vista Ultimate 64bit and also replace the 3gb ram for 8gb of ram. Now on the Dell site the fastest ram they offer is 800MHz. Does this mean the fastest ram I can purchase is 8gb at 800MHz? Can I purchase ones that are at a faster clock speed one that matches the cpu (1066MHz) or something that runs at the fastest speed for optimal performance?

Apologies if the questions don't make sense as I don't really know much about PC hardware.

Thank you in advance,
Masterson

Enter your Dell in the Crucial Memory Advisor™ tool here. MB/Chipset dictates which RAM speed is capable.

http://crucial.com/

Thank you badge for your reply.

This tool is very helpfully. But according to them I should not exceed the 4gb as per requested by the manufacturer. Will it be safe for me to go over 4gb as I was really hoping to max out the slots . Also the fastest ram they offered for my system is the PC2 6400 again due to request of the manufacturer.

I am wondering if it will alright for me to stick in ram with a clock speed that matches the cpu (1066MHz) or the fastest I can possibly get it.


Thank you again in advance
Masterson

Well, it could be your MB only supports 4 GB, I don't know. FYI, if you overclock your system (increase FSB), the RAM you are using (PC5300)will overclock along with your system. Your PC5300 667 mhz. will clock to 'near' PC6400 800mhz speeds, to at least 700 mhz or so. If you change over to PC6400 800mhz., Crucial DIMMS should run near PC8500 or 1066 mhz. Anyway, whatever RAM you have, the speed can be adjusted. Not sure what you are asking.

According to the manual online at the dell site your computer will support up to 8GB (4x2GB modules.) However, I'm not sure what overclocking you can do inside these latest XPS's. But most Dell Bios' I've seen there is no way to adjust the cpu or memory clocks. Which means the MB will be set to either run at 667 or 800 depending on what you put in. I would bet if you put 1066 in it would either not run well or more likely just run at 800. Also, can you adjust your memory voltage in the bios? Cause if not, be careful about getting memory that needs to run at a higher voltage like 2.1 or 2.2

occdavid has it right. Your board will not 'auto' set at any RAM speed above PC6400. That would have to be accompolished manually, if even available. Like occdavid, I have no idea what options are available to you in BIOS. In your case with the Dell, the 'guaranted to work' option a company like Crucial offers is a good thing. If you cannot adjust the voltage, like occdavid mentioned, you have serious limitations as to 'which' DIMMS would even work in your system. Never owned a Dell.

Sorry if I was unclear. Just trying to figure out the best ram to buy.

In regards to your advice of increasing the fsb, unfortunately because this is a Dell rig I don't think I will be able to up the fsb. Also just looking at the crucial site I can't see any PC2-8500/1066 that are 2gb dimm.

But apart from trying to find out the best ram to buy, now I would like to know if my system will accept PC2-8500/1066?

Thanks again Badge
Masterson

Even if you put PC28500 1066 mhz. 'capable' DIMMS, they would show up as PC6400 running at 800 mhz. best. They would have to be manually set to run at 1066 mhz.

As Occdavid said, PC8500 'probably' would not even run or boot your system (you probably have no voltage increase adjsutment that may be necessary to run them.)

best to stick with what Crucial (for example) guarantees will run. Hopefully Crucial's suggestion will run at 800mhz. when you install them.

What are you planning to do that requires so much memory ?

From what I understand, your FSB is actually quad pumped and your memory twice pumped. So the memory (667/2 = 333) and FSB (1066/4 = 333) are nicely matched and you might not gain any advantage from faster memory if you cannot overclock. As a result, you will be paying quite a lot to increase memory as you plan. The 3 GB is pretty close to the limit - probably about 3.2GB - on Vista Premium and you will be paying a lot to go to Vista 64 and replacing and addding faster memory. Can someone with a little more knowledge confirm or correct this?

Thank you all for your reply.

I don't actually have the system yet as it is in the process of delivery, Dell says its will take a few days.

From what you guys are saying, I might just buy some PC2-6400/800MHz just to be on the safe side. Plus I can't seem to find any PC2-8500/1066MHz 2gb dimms. I have found some DDR3 at crucial but thats out my price range.

As for the reason of wanting 8gb of ram, well I'm just being greedy But I do need a stable system that will last for a while as I do a lot of developement work and I normally have multiple memory hungry programs on at the same time and vm's. Also the regular video encoding and the usual gaming (Waiting for StarCraftII ).

I think I will shop around for some PC2-6400/800MHz 2gb dimms as advised by you guys ( the experts ). You guys know a cheap place to purchase some?

But thanks again guys for your help. I will keep you posted and let you know what I can change in the bois once my system arrives.

Thanx
Masterson

You could try taking out all the RAM that is currently in the system and purchase just 2x2GB PC2-6400 DIMMs. See if the mobo automatically sets your FSB to 800MHz after putting the new RAM in. You'll have 4GB and you can see you how you get on. If you find that you need more RAM (keep your eye on task manager - or any other method you choose) then at a later time you can buy another 2x2GB PC2-6400 DIMMs, they'll be cheaper by then too.

If you find that the system does not automatically increase the FSB to 800 and just stays at 667, you could use the 2x1GB sticks which came with the system and the 2x2GB PC2-6400 DIMMs, you'll have 6GB in total.

If money's not really an issue just go for 8GB 4x2GB PC2-6400 DIMMs and give me the ones that came in the system, or ebay them.

But will the 800MHz memory be any faster than 667MHz in a system with a 1066MHz FSB and no overclocking? And by "faster" I mean improved performance not just faster RAM speed.

I have just read a post by someone who also bought a Dell XPS 420, that PC2-6400/800MHz will work but it only gave a 10% improvement.

A 10% improvement in what?

Dell's Bios are normally locked, thus no overclocking.

Dell MBs, like all MBs are limited in the speed of the RAM that can be installed.

If Dell and Crucial both say 800MZ, then it is 800MZ.

DDR2 PC5300 667mhz = 5.3 GB/second data transfer rate RAM to CPU

DDR2 PC6400 800mhz = 6.4 GB/second data transfer rate RAM to CPU

PC6400 compared to PC5300 is about a 20% increase in data transfer rate RAM to CPU.

I would wait and check the chipset of your dell motherboard, and download the bios if you can find a link. You might be wasting your money by changing memory. The board may not change your memory speed to match the newer faster modules.

But will this theoretical increase actually translate into faster performance or will it be constrained by CPU or FSB speeds, or some other component?

If you increase your RAM speed from 5.3 GB/second data transfer rate (speed) to 6.4 GB/seconds data transfer rate (speed) and you system doesn't crash, your memory is performing at a faster data transfer rate regardless of what your CPU or FSB remained at.

Ram speed can be adjusted independently of FSB speed and/or CPU speed.

With all that said, do a search for 'memory dividers' and see what you come up in relation to what you are asking.