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Intro

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Basics - RAM Timings

Page 3
Tweaking RAM

Page 4
Updates & Final Words

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BASICS - RAM TIMINGS/LATENCIES - WHAT THE HELL ARE THOSE??

Ok, for those who do not know anything about this, RAM timings are the 2-2-2-5 and the 2-3-3-7 and the 3-4-4-8 that the veterans always talk about when it comes to RAM. Now what are these numbers really? To put things really simply, they actually refer to the delay timings of a certain stick of RAM. And as you might have figured out, less delays mean faster RAM. So, to put it simply and accurately, the lower or tighter the timings/delays, the faster the RAM is. Meaning 2-2-2-5 is faster than 3-4-4-8. Yup, told you it was simple. Please keep in mind that all the above was assuming that the clockspeed of the RAM remains the same, only timings different.

Not all RAM can run at the tightest/best timing of 2-2-2-5. Generally, high-quality lower speed RAM like DDR400 will have tighter timings, while most DDR500 RAM have loose/relaxed timings (usually 3-4-4-8).

Now, I will explain briefly the most common RAM timings for a P4 mainboard, and how they affect performance.

Refer to the picture above for what I will talk about here.

Now, get into the Advanced Chipset Features menu in the BIOS (or something similar to that, not all BIOS are the same) You will see a row of numbers like 3, 8, 4, 4 or 3, 4, 4, 8 or whatever other arrangement they might have, depending on the BIOS. These are the most important settings for your RAM. Now I will explain in minimal detail what the settings are.

DRAM Timing Selectable (Options - Manual, By SPD)
This refers to the settings of the 3 timings I will explain below. By SPD means that the timings are set by the BIOS automatically to the default suggested by the manufacturer. The timings in By SPD mode can be used as a reference/default. Since you want to tweak the settings, set this to Manual.

CAS Latency Time (Options - 2, 2.5, 3)
This refers to the Column Address Strobe delay time. Lower is better! However, in a P4 system, lowering this setting only improves performance minimally, so it might be better to increase this setting to gain stability or a higher overclock.

Act to Precharge Delay (Options - 5, 6, 7, 8)
This refers to the Active to Precharge delay time. Lower is better! However, same as above, lowering this setting only improves performance minimally, so it might be better to increase this setting to gain stability or a higher overclock.

DRAM RAS# to CAS# Delay  (Options - 2, 3, 4)
This refers to the Row Address Strobe to Column Address Strobe delay time. Lower is better! This is the most crucial setting in a P4 system! Lowering this setting improves performance quite noticeably, so you might want to sacrifice some clockspeed to lower this timing.

DRAM RAS# Precharge (Options - 2, 3, 4)
This refers to the Row Address Strobe to Column Address Strobe delay time. Lower is better! This is the 2nd most crucial setting in a P4 system! Lowering this setting improves performance quite noticeably, so you might want to sacrifice some clockspeed to lower this timing.

Leave all those other settings at their defaults.

THINGS TO REMEMBER

1. When someone refers to RAM timings as 2-3-4-5, they usually mean, from 1st number to the last number:
   1. 2- CAS latency time
   2. 3- RAS# to CAS# delay
   3. 4- RAS# Precharge
   4. 5- Act to Precharge Delay
       
2. Keep in mind that if you lower the RAM timings too much, your system be unstable or might not boot. If this happens, turn off your computer and wait at least 30 seconds. Just press and hold the INSERT key when turning on your PC again and all should be fine.
    
3. Different RAM sticks are made for different things.
   1. Some RAM sticks are built for lower clockspeeds and tight timings. For example, DDR 400 with 2-2-2-5 timings. However, RAM like this can seldom reach high clockspeeds.
   2. Some are built for super-high clockspeeds and more relaxed/higher latencies. For example DDR500 with 3-4-4-8 timings. These RAM usually cannot run at super tight timings, but can achieve speeds of 250MHz or more.
   3. There is always a compromise between clockspeeds and latency. Lower latencies usually mean lower clockspeeds. Higher clockspeeds mean higher latencies.
4. Timings and clockspeeds affect the performance of the RAM. So, the perfect RAM will be able to run at super high clockspeeds (DDR500+), and at super low latencies (2-2-2-5). However, there is no RAM that can do this at the moment.
    

Remember that a good RAM overclock does not mean the highest clockspeeds or tightest timings, but rather a good balance between the two. I cannot possibly tell each and every one of you the optimal settings for your system, as there are too many combinations. So you will have to spend some time experimenting to see which settings gives you the best combination.

I personally think that the best RAM to get for the P4 is ultra low latency DDR400/DDR433 RAM that can run at 2-3-2-6 or lower. This RAM is the most flexible to overclock with and the performance comes close to most DDR500 RAM because of the tighter timings.

Or, better still, get memory that can operate at low clockspeeds with low latencies, and higher clockspeeds with higher latencies. This way, you can tweak the settings to your heart's content! My personal favorite is OCZ PC3700 Gold Rev. 2. Read a review about this awesome memory here.

However, the best RAM may not be the easiest to tweak. The easiest RAM to overclock with is high quality DDR500 or DDR533 RAM. With this RAM, you do not have to mess around with many settings. More details on the next page.

Next Page - Tweaking Your RAM

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Copyright© 2004 by Farhan Mohamed Ali