PC2-800 or PC2-1066 for an Athlon X2 7750 (Kuma Core)?

[GilmourD]

I've searched and searched and searched and haven't come up with anything definitive... Do I want PC2-800 CAS 4 or PC2-1066 CAS5 for an Athlon X2 7750 that I plan on moderately OCing on an ASRock AOD790GX? Whichever option you pick, why?

 

[britonk]

I looked into this myself I have an ASUS M2N SLI Deluxe and am using an Athlon 64 X2. With my motherboard (and I think this may be the case with all) you only get the benefit of the 1066MHz RAM if you are using a Phenom processor. With an X2 it will run at 800MHz. So unless you plan on upgrading the CPU (and the MB can take it) get the 800MHz.

 

[haste]

Shouldnt u be able to get tighter timings with the 1066 running at a lower clock? And if you do need some headroom, its there. or if u upgrade later and need faster ram...u have it. seems like a no-brainer to me.

the price difference is so negligible, why not just get the faster ram?

 

[GilmourD]

I looked into this myself I have an ASUS M2N SLI Deluxe and am using an Athlon 64 X2. With my motherboard (and I think this may be the case with all) you only get the benefit of the 1066MHz RAM if you are using a Phenom processor. With an X2 it will run at 800MHz. So unless you plan on upgrading the CPU (and the MB can take it) get the 800MHz.

This Athlon X2 is a Kuma which is an Agena Phenom with two cores disabled.

 

[britonk]

Well as Haste says then why don't you get the 1066 RAM and try running it at 1066. If it doesn't work it will run at 800MHz and you may be able to get the 800MHz CAS timings out of it anyway.

I have heard of manufacturers limiting the clock speed of CPUs and labelling them up at something else before but never disabling cores. Surely this would be costing them more to produce and then they have to sell them at the same price as dual cores anyway. How do you know this?

 

[GilmourD]

Well as Haste says then why don't you get the 1066 RAM and try running it at 1066. If it doesn't work it will run at 800MHz and you may be able to get the 800MHz CAS timings out of it anyway.

It's not a matter of working or not working. It's a matter of which will yield actual better performance.

I have heard of manufacturers limiting the clock speed of CPUs and labelling them up at something else before but never disabling cores. Surely this would be costing them more to produce and then they have to sell them at the same price as dual cores anyway. How do you know this?

Obviously you missed the three-core Phenoms and some of the single core Athlon X2s when the dual cores just came out. It helps them sell processors that don't meet yield for quad or tri core.

 

[GilmourD]

Seems half and half so far... Any other opinions?

 

[Abit667]

I asked this last week and after looking into it a bit more I found the performance difference is pretty small, and outside of benchmarks probably not too noticeable...

Getting the 1066 will give you more headroom if you need it, and you could always run at 800, or anywhere in between pretty safely. The only problem I've had with 1066 memory is that most of it needs a ton of voltage to work right at 1066 and even then isn't always perfectly stable. This might not be a problem for you, but if you choose to add more memory later you'll have to find either the same ram or something else that will work at the higher voltage.

In the end I chose 8 gigs of DDR2 800 with good timings and normal voltage and the performance benefit of 8Gb and not having to worry about stability was worth it for me.