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Mixing RAM timings and another question

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October 30, 2010 4:59:42 PM

Hi everyone.

I'm considering adding more RAM to my computer, but I just wanted to sort a few things out before I did. I currently have 2GB DDR2 RAM, with 4-4-4-15 timing (my extra question is about this, later on), and I'm wanting to add another 2GB RAM so that I'll have 4GB. I'm currently looking at buying this 2x1GB RAM kit, which has 4-4-4-12 timing, and also operates at 2.0V. Will mixing RAM like this cause problems? I can't find any RAM with exactly the same timing as my current RAM either, so if I can't mix the RAM, I might have to buy a whole new set of RAM...(any advice on this? :p )

Now my extra question... The motherboard I have is a GIGABYTE GA-M57SLI-4 Rev2.0, and the RAM I have is the OCZ FlexXLC CL3 model, however the CL3 comes from using an EPP feature on the motherboard, which apparently my motherboard doesn't have. But CPU-Z says otherwise - under the SPD tab, it says in the SPD Ext. box that I have EPP 1.0. Trying to set the CAS timing in the BIOS to 3 stops my PC from booting, so I have to reset the BIOS. I know if I try and use this with new RAM, then it definitely won't work, but I was just curious about this.

Thanks in advance! :) 
a b } Memory
a b V Motherboard
October 30, 2010 6:03:32 PM

Mixing RAM is not an issue. As long as the voltages and timings are the same it'll work fantastic (and even if they aren't, it's easy enough to change them). Make sure that your OS is 64-bit, as a 32-bit OS will NOT recognize 4GB of memory.

As for the second question, I'm not 100% sure, but I'm fairly certain CPUz just lists the compatible timings for the memory based on what the memory itself says it's capable of. Hopefully somebody can confirm/correct me.
a c 347 } Memory
a c 717 V Motherboard
October 30, 2010 7:11:39 PM

I, firsthand posting here, can tell you it is NOT a good idea.

GA-M57SLI-S4 - http://www.gigabyte.com/products/product-page.aspx?pid=...
OCZ Tested - http://memoryselector.cnetchannel.com/ocztech/result.as...

Is this you current RAM {OCZ FlexXLC PC2-6400 CL3 DDR2} http://www.dvhardware.net/review126_ocz_flexxlc_cl3.htm...

DDR2 800MHz 3-4-4-15 @ 2.1V {current}
DDR2 800MHz 4-4-4-12 @ 2.0V {proposed}
======================
800MHz 4-4-4-15 @ 2.1V -> worst of each; both have an operational Voltage variances ± 0.2~±0.3 V.

If you have the water cooled OCZ FlexXLC then it's nothing I would mix-match; don't mix SS with DS either.
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October 30, 2010 8:04:13 PM

Quote:
As for the second question, I'm not 100% sure, but I'm fairly certain CPUz just lists the compatible timings for the memory based on what the memory itself says it's capable of. Hopefully somebody can confirm/correct me.

That would make more sense. Every source I find tells me my motherboard doesn't support EPP.

Quote:
Is this you current RAM {OCZ FlexXLC PC2-6400 CL3 DDR2} http://www.dvhardware.net/review12 [...] c_cl3.html

DDR2 800MHz 3-4-4-15 @ 2.1V {current}
DDR2 800MHz 4-4-4-12 @ 2.0V {proposed}
======================
800MHz 4-4-4-15 @ 2.1V -> worst of each; both have an operational Voltage variances ± 0.2~±0.3 V.

That's the RAM I meant. But actually, it's currently running with 4-4-4-15 timing, like I said in my first post. My motherboard doesn't support the required feature to get the CL3 timing. What are the dangers of mixing RAM with different timings? And would you recommend I just replace my current RAM with some new ones? If so, I may just buy some cheap-ish CL5 2x2GB RAM. I'm not too worried about small performance drops, and I doubt the difference between CL4 and CL5 would be noticeable.
a c 347 } Memory
a c 717 V Motherboard
October 30, 2010 8:29:07 PM

The PRIMARY concerns are that the Memory Controller will fail, and (1) set of RAM is essentially turned-off {ignored} by the BIOS. This situation is a 5-10 times per day posting question; one set works and the other doesn't -- please help me fix... Also, some RAM IC's aren't compatible - period.

Matching RAM is smartest choice, as I mentioned Certified or Tested. My preferences are: Corsair, G.SKILL, Mushkin, Kingston -- and Crucial {budget RAM}.

The Timings concern me the least; choose the slowest of each set. It's the Speed, Voltage, and IC that cause the problems; plus NON-hand/BIN matched sets cause issues.

edit: I am NOT saying that your mix-matched sets won't work, but I am clearly stating they "may not" work.
October 30, 2010 8:44:14 PM

Thanks, that makes things clearer for me. I guess that's enough reason for me to replace my RAM! I don't really want to buy some RAM and then find that they don't work with my existing RAM, and then having to buy more RAM anyway.
a b } Memory
November 1, 2010 9:03:51 AM

If that happens it's just because of dead sticks, or mobo support doesn't support the memory. I won't grudge, but 70% chance that it will work. Only 30% doesn't work, and it's caused by dead sticks, (which you can RMA) or mobo support.
For the proof, you can look at my rig. Different brands are no problems. The thing's matter is to adjust voltage & timing according to worst condition like above this..

jaquith said:
DDR2 800MHz 3-4-4-15 @ 2.1V {current}
DDR2 800MHz 4-4-4-12 @ 2.0V {proposed}
======================
800MHz 4-4-4-15 @ 2.1V -> worst of each; both have an operational Voltage variances ± 0.2~±0.3 V.


However, buying same brand, speed, and timings is better.
!