Can we connect different brand of RAM in same PC

The problem that happens when we connect two or more, different brand of RAM or different size of RAM or different frequencies in a same PC is called FREQUENCY MISMATCH. This effect is not found most of the time immediately when we connect and power on the PC. This does not give any RAM beep to warn you. When there is a mismatch we cannot boot the OS properly, cannot copy files from one location to another, cannot compress or decompress files, and cannot run application that requires RAM resources. Of course this will show increase in size after connecting, but know that you are going to damage your RAM.

The cause for this problem is the RAM cannot withstand the operating frequency of each other as each RAM will produce an error while working. This varies with manufacturer and when this exceeds the limit, the RAM chip gets damaged. This slowly develops and at a stage creates trouble.

I myself practically tested this effect with two different size of RAM (128MB+64MB) showing 192MB, I could use the PC for about three months without any problems but later the OS crashed. I tried loading new OS, but it failed to install. Then I found that one of my RAM (64MB) developed unrecoverable damage in it.

Even after knowing this problem I made a mistake. In my office I connected four RAM of same frequencies, same size but different brands. For one week only the PCs were stable and I got the same annoying symptoms. Then when I tested I could find a RAM damaged internally and giving problem in performance. Please protect your PC without damaging hardware. So guys do not try this at home and cause damage to your loving PCs.

Having a single RAM module is OK but you might lose certain performance like dual channel mode. When buying two or more RAM for a single PC, see that you get the similar RAM delivered in the SAME BATCH. This will avoid any problems regarding the Frequency Mismatch.

Difference between DDR1, DDR2 and DDR3

When we buy a PC we see the capacity of RAM by its size, there is another factor to consider, it’s Frequency or Working speed of RAM. RAM frequency has been updated most of the time and we are not able to judge what we need to buy. Here is a list of RAM upgrades and specifications. Plan before you buy one of them.

DDR1 is the first of the Series of the DDR-SDRAM and comes in the following series. The technology and its stable operation led to the invention of the latter memory modules. This powered the Entry level Pentium 4 series of boards and was a breakthrough from the older SDRAM.
DDR SDRAM: Double Data Rate SDRAM (DDR200, DDR266, DDR333 are standard)
PC1600 (DDR-200 SDRAM); Clock Speed: 100MHz, Data Rate: 200MHz, Throughput 1600MB/s
PC2100 (DDR-266 SDRAM); Clock Speed: 133MHz, Data Rate: 266MHz, Throughput 2100MB/s
PC2400 (DDR-300 SDRAM); Clock Speed: 150MHz, Data Rate: 300MHz, Throughput 2400MB/s
PC2700 (DDR-333 SDRAM); Clock Speed: 166MHz, Data Rate: 333MHz, Throughput 2600MB/s
PC3000 (DDR-366 SDRAM); Clock Speed: 183MHz, Data Rate: 366MHz, Throughput 2900MB/s
PC3200 (DDR-400 SDRAM); Clock Speed: 200MHz, Data Rate: 400MHz, Throughput 3200MB/s

DDR2 Memory is Second series of memory developed from the DDR1. The speeds and built technology of these memory modules is much superior to the DDR1. This memory was also launched in a low and affordable cost which led to a great increase in memory sales. The high speed version of this memory boosts performance of gaming and animation related task.
DDR2 SDRAM: Double Data Rate SDRAM II (Quad Edge Clock Rate, 1.8v signaling), Second Generation
PC2-3200 (DDR2-400 SDRAM); Clock Speed: 100MHz, Data Rate: 400MHz, Throughput 3200MB/s
PC2-4300 (DDR2-533 SDRAM); Clock Speed: 133MHz, Data Rate: 532MHz, Throughput 4300MB/s
PC2-5300 (DDR2-667 SDRAM); Clock Speed: 167MHz, Data Rate: 667MHz, Throughput 5300MB/s
PC2-5400 (DDR2-675 SDRAM); Clock Speed: 167MHz, Data Rate: 667MHz, Throughput 5400MB/s
PC2-6400 (DDR2-800 SDRAM); Clock Speed: 200MHz, Data Rate: 800MHz, Throughput 6400MB/s

DDR3 Memory is the Third generation of DDR memory. It has been launched and is priced low to suit most of the PC consumers. This memory is expected to power the entry level servers, Gaming PCs and High-end Graphics related tasks. Sure this will make ours a high-end desktop PC.
DDR3 SDRAM: Double Data Rate SDRAM III (Quad Edge Clock Rate, 1.5v signaling), Third Generation
PC3-6400 (DDR3-800 SDRAM); Clock Speed: 100MHz, Data Rate: 800MHz, Throughput 6.40GB/s
PC3-8500 (DDR3-1066 SDRAM); Clock Speed: 133MHz, Data Rate: 1066MHz, Throughput 8.53GB/s
PC3-10600 (DDR3-1333 SDRAM); Clock Speed: 166MHz, Data Rate: 1333MHz, Throughput 10.67GB/s
PC3-12800 (DDR3-1600 SDRAM); Clock Speed: 200MHz, Data Rate: 1600MHz, Throughput 12.80GB/s

Intel Nehalem Microarchitecture

NEHALEM Features:
 Intel Quick path Architecture
 High-k process technology
 45nm presently and 32nm in future
 Inclusive last level cache
 SSE4.2
 Loop stream detector
 Simultaneous multi threading

These features are explained below…

One of the key features that NEHALEM has is the Quick path architecture. The two components are quick path memory controller and quick path interconnect. As memory controllers are integrated along with the processors the Bandwidth is increased rapidly boosting speeds of data input for the CPU’s. This also helps in integrating multi processor.

Intel Nehalem is built with Industry’s first, High Density transistor with High-k process technology coming in 45nm. The traditional Silicon Gate and Silicon Dioxide insulator is removed in transistors because for the electron leakage problem and comes equipped with Metal gate and Hafnium insulator. This Technology can power Notebooks, Desktop to High end Servers with energy efficiency.

Inclusive last level cache is introduced in Nehalem. This improvement eliminates unnecessary core snoops to reduce latency and improves cache performance. The older method is slower called Exclusive level cache.

Nehalem has 7 instructions set including 4 of SSE4.2. This helps better text and string processing boosting performance for XML parsing (communication protocol). Compared to older CPU’s, which reads text, bit by bit. The new feature lets us compare text in length of 16 bytes. This ultimately reduces the state transitions requirement.

The Loop stream detector identifies repetitive instruction sequences and queues the loop without getting it again from the source. This reduces power as it gives rest for other branch prediction, fetch and decode units.

Advanced features of Nehalem micro architecture are increased parallelism, more efficient algorithm and improved branch prediction.

Nehalem has a great feature called Simultaneous multithreading (SMT). It helps to run 2 threads per core. In Normal QUAD core processor, it sends data to cores which will process one thread per core. But with SMT present day multicore processors handle 8 threads (2 per core). future plan is to increase up to 16 threads. Just adding more and more Cores is not energy efficient way, with SMT we can increase the threading. This gives higher and higher performance for the growing needs of application. Ultimately reduces power consumption.

The full featured Nehalem is expected to be launched in November or December 2008. The Next generation 32nm processors will come later.