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Adding additional RAM

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December 9, 2004 4:48:40 AM

I have an ASUS P4C800-E Deluxe motherboard with a P4 3.2ghz processor. I have 2x 512 MB APACER chips (PC3200). I'd like to add another gigabyte worth of RAM. But I'm not sure If I can add faster RAM. I was taking a look at CORSAIR XMS Dual Channel PC4400 chips. I was wondering if I installed this RAM (or any other RAM faster than pc3200) would it run at 4400 or would it run at 3200 (the speed of the slowest pair).

I've looked this stuff up but am still confused. I first read that it will definitely run at the speed of the slowest RAM but then I read some other place that I might be able to buy faster RAM and it will run at the fast speed.

Money's not too much of a problem but I'd like to save money if i can and get a 10000 rpm sata hard drive.

Thank You for reading.

More about : adding additional ram

December 9, 2004 2:38:52 PM

Memory will run at the speed set by the fsb and memory ratio of the board.

As far as I know (and I'm pretty sure that includes 100% of consumer-type motherboards), all installed memory chips have to run the same speed and timings - so if you have some PC3200 and some PC4400, unless your PC3200 can run at PC4400 speeds (not very likely - but maybe possible with relaxed timings), you will be running at PC3200.

Did that make sense? Clear as mud? :) 

Mike.
a b } Memory
a b V Motherboard
December 9, 2004 9:48:12 PM

Fishman is onto it. You have PC3200. Your PC3200 will operate at a 1:1 ratio with your CPU bus clock. That is, you have a QDR 800 bus with a 200MHz clock, you have DDR400 with a 200MHz clock. If you overclock your CPU bus, you will also overclock your RAM bus.

If you install PC4400 by itself, using the 1:1 ratio it will also run at 200MHz clock, DDR400. Of course PC4400 allows you to overclock the CPU at that 1:1 ratio without overstressing the RAM.

All the RAM will run at the same clock. So having both PC3200 and PC4400 installed, your RAM speed is limitted to how far you can overclock the PC3200. Say your PC3200 can be overclocked by 10%, that means you raise your CPU bus from 200 to 220MHz, your RAM clock gets raised from 200 to 220MHz, and all the RAM will run at DDR440, just a hair above PC3500 speed.

So mixing faster and slower modules only makes sense in rare circumstances where the faster modules are cheaper. For example, PC2700 is often cheaper than PC2100 because PC2100 is no longer in production. So mixing those allows you to get "really good PC2100" from PC2700. But you're not in that situation of saving money.

Don't get ultra-high-speed RAM unless you plan on overclocking, and if you do that, you'll have to get rid of the PC3200.

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December 10, 2004 5:20:59 AM

Thanks for the replies. This really helps (and saves money :) . I think i will just get similar RAM to what I already have and get some suped up RAM when I get a whole new system.
!