After building a new computer I encountered problems with my Sony (DRU810A) DVD+/-RW drive. The computer is setup with a Samsung DVD-ROM drive as the master, and the Sony DVD burner as slave. The Samsung drive works correctly, but the Sony drive does not work, and the drive door on the Sony drive keeps opening and closing by itself. I have tried swapping the drives between master and slave but this does not resolve the issue. A second question is the computer has 1.5 GB RAM in total, consisting of 2x DDR400 512 MB sticks and 1x DDR2700 512 MB stick. If I set the RAM speed to 400, only 1 GB of memory is detected in the machine. However, if I slow down the RAM speed the entire 1.5 GB of memory is recognised. So, would the computer run faster if I remove the DDR2700 RAM and set the RAM speed to 400?

The behaviour you describe of the Sony DVD drive is indicative of a hardware fault. Firstly, make sure the IDE cable is correctly connected to the drive. Next, verify the jumpers on both the Samsung and Sony drives are set correctly to ‘master’ and ’slave’. If you are using ‘cable select’ I suggest manually setting the jumper to ‘master’ and ’slave’ to ensure the computer is correctly identifying each device. Be aware: if you manually set the Sony drive to ’slave’ (or ‘master’) you will also need to also configure the appropriate jumper setting on the Samsung drive. Should the jumpers be set correctly, the diagnosis appears to be that the drive is faulty. This conclusion is also justified considering the drive (presumably) has not worked and always exhibited this behaviour from when you originally built the computer. In this case, you should contact either the retailer or manufacturer to enquire about obtaining a replacement drive under warranty.

Regarding your question about RAM, understanding the concepts and terminology in RAM is a tricky process. The RAM in your computer appears to be DDR SDRAM (double-data-rate synchronous dynamic random access memory), which is a relatively common memory type. The first concept we need to understand is the difference between the chip specification and memory module/stick specification. When we talk about the chip specification, this means the individual memory chips on the memory module/stick. These have ratings such as DDR-200, DDR-266, DDR-333 and DDR-400. Each of these ratings defines the speed of the RAM. For example, DDR-400 chips are specified to run at 200 MHz. Next, we talk about the memory module/stick specification. This refers to the memory stick itself (which contains the memory chips). These have ratings such as PC-1600, PC-2100, PC-2700 and PC-3200. Each of these ratings specifies the type of chip used on these memory sticks, and the speed at which the chips operate. For example, PC-2700 memory modules are designed to run at 166 MHz, with DDR-333 chips. Likewise, PC-3200 memory modules are designed to run at 200 MHz with DDR-400 chips. So, from the description of your computer setup you have 2x 512MB SDRAM PC-3200 modules (with DDR-400 chips) and 1x 512MB SDRAM PC-2700 module (with a DDR-333 chip).

Now we have the terminology out of the way, we can discuss the implications of mixing different speeds of memory. Since you have two PC-3200 memory modules running at the faster speed of 200 MHz, plus one PC-2700 memory module running at the comparatively lower speed of 166 MHz, you are mixing the RAM speed. Generally, if you mix RAM speeds the system will default all the RAM to the slower speed. This is probably why the slower RAM is not recognised when you set the BIOS to the faster RAM speed, but the slower RAM is recognised when you set a slower RAM speed.

Now, you must consider the trade-off between having slower RAM, and having more RAM. This trade-off really depends on your usage of the computer. If your computer regularly runs low on memory with only 1 GB of RAM installed, installing the PC-2700 memory module (increasing system memory to 1.5 GB) should benefit performance. Even though the entire system RAM will be slower, accessing this (marginally) slower RAM will still be significantly faster than the computer having to swap data between the RAM and hard drive (virtual memory) due to the lack of available memory. However, if you are not fully utilising the current 1 GB of RAM, installing the slower PC-2700 RAM will likely decrease system performance. This is because the computer will not utilise this extra memory, since the existing 1 GB of memory is not being fully utilised, so all you are doing is slowing down the entire system memory! As you can see, the decision whether to install the slower memory depends on your computer usage. I suggest using the Windows Task Manager to monitor available memory. In Windows XP, press CTRL-ALT-DEL and then click the ‘Performance’ tab. In the ‘Physical Memory (K)’ area, look at ‘Available’. If you notice this number getting low (be aware, it is measured in kilobytes, so 1 MB = 1000 KB) this means you are getting close to exceeding your system RAM. In this case, it may be worthwhile installing the slower RAM to increase total system RAM.