DDR explained- DDR or Double Data Rate memory modules only operate at half the rated module speed- that it to say, for example- a DDR memory module that is rated at say PC-2100 with a rating of 266MHz is actually 2 times 133. The reason for this is that DDR memory operates at twice the Theoretical Bandwidth of previous PC-133 SDRAM modules, and hence the rating. This applies for all DDR memory modules to date. Certain DDR modules to possibly avoid are PC 2400 and PC 3000, why might you ask, because they are generally overclocked versions of previous slower DDR memory modules. Most DDR memory modules will have latencies of 2 or 2.5 the lower the number the faster, and the more expensive. The Asus A7N8X can only use DDR memory modules.
Memory is very straight forward, with two things to note:
First, DDR memory modules have to be installed correctly. That is to say: the memory module has a locator depression in the module located off center that must align with the memory slot located on the motherboard. A quick comparison of the two will exemplify this.
Secondly, it takes a bit of pressure to install the modules into the motherboard. The locking tabs must be in the "open position" during installation. Installation procedures are as follows: use even, direct pressure, and using both thumbs, one at the top and one at the bottom of the module to push it into the slot. When fully seated, the locking tabs will close on their own accord and securely lock the module in place.
Your memory controller used with the A7N8X Deluxe is technically two separate memory controllers contained in one chipset (generally referred to as the North Bridge) Slots one and two are memory channel 1 and slot 3 is memory channel two. (as viewed from left to right)
Dual-channel To implement Dual channel operation you must have two or three, electrically equal memory modules preferably of the same brand. Dual channel kits work nicely for this purpose.
Installation for dual-channel operation: you may use slots 1 and 3 or slots 2 and 3 (as viewed from left to right). If you have three modules - all 3 slots may be used. Again, and I stress this, it is absolutely imperative that the modules "electrically" match for correct dual-channel operation. If this is not adhered to you will experience problems.
Note: it is preferable when using three memory modules to have each channel match in size. For example - slot 3 could have a 512 memory module and slots 1 and 2 could have two 256 memory modules, this generally provides the best performance/compatibility when using three memory modules.
Single Channel Single channel operation memory placement is generally viable in any one of the three slots (slots one or three are generally preferred).
Recommended available memory modules are as follows:
DDR modules - PC2100, PC2400, PC2700, PC3000, PC3200, PC3500, PC3700 and PC 4000 soon!
Each model number represents each memory module's rated speed. Naturally, the higher the rating the faster the module; and generally, the more expensive. The most common modules for use with Athlon XP processors are from the PC2700 range and up. However, this motherboard supports all of the module speeds listed. Accordingly, you must match your memory selection to the rated speed of your processor, more on this is in the BIOS section page.
ASUS memory explanation web page see it here.
When building a new system it is advisable to test the memory to make sure it is functioning correctly. Many users perform this test using Memtest86. Memtest requires up to 5hrs 30mins to run one full cycle of 11 tests. Generally, with the speed of modern CPU's the test will finish sooner, but let the test complete. It is very common to recieve errors on test 5, and occationally test 8. Here is a snip-it from the Memtest website concerning this issue-
" Sometimes memory errors show up due to component incompatibility. A memory DIMM/SIMM may work fine in one system and not in another. This is not uncommon and is a source of confusion. In these situations the components are not necessarily bad but have marginal conditions that when combined with other components will cause errors.
I have had numerous reports of errors in only tests 5 and 8 on Athlon systems. Often the memory works in a different system or the vendor insists that it is good. In these cases the memory is not necessarily bad but is not able to operate reliably at Athlon speeds. Sometimes more conservative memory timings on the motherboard will correct these errors. In other cases the only option is to replace the memory with better quality, higher speed memory. Don't buy cheap memory and expect it to work with an Athlon! On occasion test 5/8 errors will occur even with name brand memory and a quality motherboard. These errors are legitimate and should be corrected.
I am often asked about the reliability of errors reported by Mestest86. In the vast majority of cases errors reported by the test are valid. There are some systems that cause Memtest86 to be confused about the size of memory and it will try to test non-existent memory. This will cause a large number of consecutive addresses to be reported as bad and generally there will be many bits in error. If you have a relatively small number of failing addresses and only one or two bits in error you can be certain that the errors are valid. Also intermittent errors are almost without exception valid. Frequently memory vendors question if Memtest86 supports their particular memory type or a chipset. Memtest86 is designed to work with all memory types and all chipsets. Only support for ECC requires knowledge of the chipset.
All valid memory errors should be corrected. It is possible that a particular error will never show up in normal operation. However, operating with marginal memory is risky and can result in data loss and even disk corruption. Even if there is no overt indication of problems you cannot assume that your system is unaffected. Sometimes intermittent errors can cause problems that do not show up for a long time. You can be sure that Murphy will get you if you know about a memory error and ignore it.
Memtest86 can not diagnose many types of PC failures. For example a faulty CPU that causes Windows to crash will most likely just cause Memtest86 to crash in the same way. "
So as you can see there are a wide varity of errors and THEIR cause are numerous, it simply is best to run a good high quality name brand memory module(s) from the beginning of any new system build.