Doing a little upgrade on my eMachines computer Nothing too serious - I want to upgrade my RAM from 512MB to 768MB I've just bought a 256MB stick of Elixir DDR333 of eBay for £9. It will accompany a stick of Samsung 512MB DDR333 that originally came with the eMachines computer. Have I made a good choice buying the Elixir stick? Are they generally a good brand?
I've never heard anything negative, outside of maybe one or two people that misdiagnosed the problem.
There is something I don't understand. Back in the days of the Pentium 3, if a processor ran on a 133MHz BUS, then the RAM would need to be 133MHz. The CPU external BUS and address BUS should always be equal. So with that theory in mind, can you explain this: My Motherboard Specs: Processor Support for an Intel® Pentium® 4 processor in an mPGA478 socket with a 400/533 MHz system bus Support for an Intel® Celeron® processor in an mPGA478 socket with a 400 MHz system bus Chipset Intel® 845GV Chipset Memory Two 184-pin DDR SDRAM DIMM sockets Support for single-sided or double-sided DIMMs (DDR 333/266/200) Support for up to 2 GB system memory The maximum supported RAM speed is 333MHz, whilst the maximum supported CPU bus speed is 533MHz! How can this be? Surely if I wanted to run a CPU with a 533MHz bus, i'd need to buy 533MHz memory? As you can see, I am still stuck in a Pentium 3 world
SDRAM was SDR SDRAM, single data rate. But we just called it SDRAM and DDR SDRAM 'DDR'. Double Data Rate. DDR passes data on the rise and fall of the clock, so it's effectively doing twice the work. DDR @ 100MHz is equal to SDR @ 200MHz. That's PC1600. PC2100/DDR266 is 133MHz, PC2700=166MHz, PC3200=200MHz. The P4 uses a quad-pumped FSB. There's a base or reference clock, which the multiplier uses for the CPU's clock speed. A 1.7GHz P4 uses a 17x multiplier and 100MHz reference clock. The FSB is 4x that reference clock. If the reference clock was 133MHz, the FSB would be 533 (not exactly if you do the math, but bear with Intel on this). A 200MHz reference clock would give you an 800MHz FSB.
This is where I get confused! is this similar to the DDR theory? The CPU external bus works on the rise and fall of the clock? Why not just increase the motherboard bus speed? Actually, based on the motherboard specs I posted earlier, can you give some examples of suitable Celeron and Pentium Processors and the speed of RAM i'd have to use with them? I might get it that way
DRAM needs to be refreshed, and we're only officially getting to DDR 800 (well, DDR2-800). The idea would be nice, but you'd have to have a heavy memory divider somewhere. With the P4 and older Athlon XP, this would really kill performance. The K8 design wouldn't be affected, however, due to the on-board memory controller implementation. Faster RAM is available, SRAM (Static RAM), but it's extremely expensive. The L1/L2/L3 caches are made up of the stuff, and why larger caches on a CPU rapidly increase the price. You'd probably pay $1,000 for 128MB if we were using SRAM. SRAM can run at the full speed of the CPU and that's part of the reason it's so expensive. DDR only works on the rise and fall of the clock, unlike SDR SDRAM that only works on the rising edge of the clock. The FSB/external clock does not operate on the rise and fall of the clock.
I've had Elixir memory before. Memtest86 showed plenty of errors after 3 months. This is actually the memory that drove me to Kingston. So I can't be totally ungrateful.
Basically my comp has an old style Celeron 2.8GHz that has a 400FSB. Am I right in assuming that I only need PC1600 RAM with this processor? The reason I got confused is because emachines have included PC2700 RAM, not PC1600. Because the Celeron is 400FSB, does that mean the PC2700 RAM is only working at PC1600 speeds? EDIT: Is PC1600 still in production? I can't find any for sale on the internet!
PC1600 would be sufficient but it'll be hard to find. I understand you don't live in the US but newegg still has KVR PC2100 256mb sticks for under $30. Maybe you can find some where you live.
Even if you found PC1600, it'd be cheaper to just snag PC3200. RAM ratings (PCxxxx) are like tire speed ratings: they're the maximum rated speed, and running slower than that speed won't hurt anything. Kingston ValueRAM is a safe bet for something cheap, not to mention pretty easy to find just about anywhere. Corsair's value stuff would be another good choice, but, at least here in the US, it's not as easy to find in most retail stores.
Okay, thanks guys. BTW, does the new Intel Core 2 Duo have a quad pumped FSB or have Intel increased it further?
