Member Avatar for oenone

Hey all, I'm in the process of choosing parts for a new system I plan to build, but I always get horribly confused when it comes to choosing RAM. I'm planning on getting an AMD 64 3800+ processor. My first question is would it be better to take advantage of the AM2 platform so I can use DDR2 memory, or should I stick with 939 to save some money. Second, what's a good memory speed to pair with this processor? (I don't want to blow a bunch of money on expensive memory only to learn it has to run at a slower speed to work with my system :P)

Thanks for your help

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As pointed out, the motherboard/platform ultimately determines whether you use DDR or DDR2, so pick the socket you want first. is also on the right track — "faster" MHz on DDR2 doesn't automatically mean lower latency in real work. Below are concise, practical points to fill gaps in the thread and help you decide.

A quick way to compare modules is to convert CAS (CL) into nanoseconds: CAS_ns ≈ CL × 2000 / (MT/s). Examples: DDR400 CL2 ≈ 10 ns; DDR2‑667 CL4 ≈ 12 ns; DDR2‑800 CL4 ≈ 10 ns. That shows why some DDR2 parts with higher CL end up similar to DDR1 in real latency even though their advertised MHz are higher.

Buying and setup tips:

  • Prioritize a matched dual‑channel kit and capacity first — a full 1GB or 2GB dual‑channel kit beats tiny gains from tighter timings.
  • Check the motherboard manual/QVL for supported speeds and correct slot population. Motherboards will often default to the slowest supported timings/speed.
  • Match voltages (typical: DDR1 ≈ 2.5V, DDR2 ≈ 1.8V) and update the BIOS if the board has early AM2/DDR2 firmware issues.
  • If you want to tune for performance, set timings manually in BIOS rather than relying on automatic presets.

Troubleshooting: if you see instability, try one stick at stock timings, run Memtest86, reseat modules, and reset CMOS before tweaking voltages or timings.

Recommendation summary: for best short‑term price/performance in mid‑2006, socket 939 with a solid DDR400 CL2 dual‑channel kit is a safe, cost‑effective choice. If you want longevity and an upgrade path, pick AM2 and a low‑latency DDR2 (667/800) kit — just expect to pay a premium.

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Member Avatar for knsljo

What memory you choose is dependant on the type of motherboard not CPU. It depends on the make, model & bus speed. What motherboard do you have?:?:

Member Avatar for oenone

What memory you choose is dependant on the type of motherboard not CPU. It depends on the make, model & bus speed. What motherboard do you have?:?:

Sorry I should probably clarify. I meant that I am currently deciding between an AM2 3800+, an AM2 mobo(most likelyhttp://www.newegg.com/Product/Product.asp?Item=N82E16813131022&ATT=13-131-022&CMP=OTC-d3alt1me ), and DDR2 RAM and a 939 3800+, a 939 mobo(DFI Lanparty Ultra), and DDR RAM. My question is what is a good memory speed to pair with that CPU in the $100-$200 price range, and is it worth the extra money to switch to an AM2 mobo with faster DDR2 RAM.

Thanks for your help

Member Avatar for nizzy1115

DDR2 Ram isnt that much faster, if any at all. It may appear so because they have "faster clock rates", but the fact that most DDR2 ram has such high latencies, they about equal out with DDR ram with lower latencies. However, they have been improving on the manufacturing of DDR2 ram to get its latencies down lower. If you plan too keep the system for a while and upgrade, i would suggest to get DDR2. However, if you plan to build whole new systems every few years, save the money and get some CL 2.0 DDR.

Member Avatar for oenone

DDR2 Ram isnt that much faster, if any at all. It may appear so because they have "faster clock rates", but the fact that most DDR2 ram has such high latencies, they about equal out with DDR ram with lower latencies. However, they have been improving on the manufacturing of DDR2 ram to get its latencies down lower. If you plan too keep the system for a while and upgrade, i would suggest to get DDR2. However, if you plan to build whole new systems every few years, save the money and get some CL 2.0 DDR.

Thanks for your advice. Would DDR400 memory with 2.0 latency be sufficient for a 3800+? Or should I be looking for something slightly faster.

Member Avatar for nizzy1115

Nope that sounds perfect. You really cant get faster than that. Just make sure you use dual channel memory and you should be set :)

Member Avatar for oenone

Alright thanks for the help :)

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