Should I mix two 512MB CL 2.5 RAM sticks with CL3 512MB?

Well, the title says it all. I could add 512MB to the current gig of RAM I have now but I would need to increase the timings.

A friend of mine says keeping low latency is important - but then he has never felt the desire to do huge fluid simulations in Blender. :smiley:

I don’t think I could run dual channel with three RAM sticks - but then I could increase my RAM by 50%. What should I do?

The RAM will be taxed by computer games (Doom 3, Half Life 2, FEAR) and CG. So where does the balance lie?


PS> I’m not really an overclocker/hardware freak but the RAM is Corsair DDR3 CL2.5 (If I remember correctly). The other RAM stick is unbranded CL3 RAM that came with the computer - I will build my own next time!

It ain’t broke. Don’t do it.

Latency does play a role, but to be fair, using ram at CAS 3 instead of 2.5 won’t really matter ‘too’ much to be honest. Fluid sims obviously require ram, but in blender’s case it does a lot of temp file creation. Fluid sim is also more likely to be CPU intensive than anything else I reckon. :wink:

Depending on your mobo, I think you can get away with it. I’ve got an Asus A78NX Deluxe and originally had two 512MB Corsair 3200 DDR modules in dual-channel (2-3-3-6 timings). I inherited another 256MB module of the exact same brand and model, popped it in and the board kept the dual channel status and still works fine.

I think it’ll be hit and miss on this one.

Just so you know, PC RAM nowadays is pretty much DDR-1 or DDR-2. DDR3 features on quite a few mid-range and high-end graphics cards, but not as yet in the PC arena.

Since your 3rd module is generic, I’d be dubious about trying it with the good quality Corsair RAM you have.

Just give things a go and see :smiley:

Thanks for the advice PolygoneUK!

Well, I have actually coded the same algorithm as used in the Blender sim - and trust me it is memory limited! A DimensionDimensionDimension192 array has to be declared at the minimum and that gets pretty big! n_t used 16GB to render the really high res simulations I think.

I shall try sticking in the RAM stick I think. Worth having a big more memory I suppose.

As for the DDR3 thing - that must have been the memory on my Geforce 7800! That is how I got confused. It is a nice card - but now I’m broke! :smiley:

Hmm…random anecdote: my computer came with a 150W power supply but this 7800 asks for 400W minimum. Too broke to buy a new PSU, I hotrigged a 350W PSU I had lying around by sending the connectors through the back of the case and leaving a PSU outside. So 150W powers the processor, hard drives, DVD writers/readers, sound card etc etc and a 350W PSU is dedicated to the graphics card. Needless to say it looks a mess.

Anyway, thanks again for the advice!


you will suffer a drop in preformance with that stick of ram. it will drop out of dual channel, and bump up to cas 3. if you want to see how bad, download sisoft sandra and do the ram benchmarks before and after.

the difference between the timings is also huge.

in a review of ram and overclocking (ocz el platinum rev 2) it drops with increases…
the ram will go to 230mhz at 2-2-2-5 and have ~4500 but, at ~240 it drops its score down to ~4250

do a test and see, you may not notice a difference but there will be a difference. most likely a negative one. some games may take advantage of your ram, however others may crap out on you. also check and see if your mobo will let you run in single channel, i think msi have problems with that sort of thing

How can you state that for sure? You don’t know what mobo Koba is running… (or maybe you do) :wink: I don’t know what board Koba is running. Like I said, I run an Asus with all 3 slots occupied, the bios happily reports 1.25GB of Dual-Channel RAM (with 2-3-3-6 timings @ 200Mhz). My benchmarks did not suffer, my CAS latency value did not change, and my system has been rock-solid for over a year.

It’ll be hit and miss depending on how Koba’s board interprets the RAM.

Note that Koba’s concerns were only related to the CAS Latency value. He/she’s running 2.5 and is concerned about going RAM running at 3.

Those values you quoted are super-low latency values. I mean, come on… 2-2-2-5 for goodness sakes (Running at 230Mhz too I might add). Of course THAT will be damn fast and be visible.

If Koba’s RAM is on say… 2.5-3-3-7 timings @ DDR400 (200Mhz), I think he/she won’t notice much of an impact if those turn into 3-3-3-7.

But 2-2-2-5 @ 230Mhz in an overclocking review. Man, compairing apples and oranges or what :wink:

approx 5% speed increase in things below 1Gig of usage. but for things over 1 Gb of usage (i hit more than 1Gb each day) it will be worth it.

my 2GB of ram is all CL3. They just don’t have CL2 1GB cards (the stuff they say is CL2.5 was majorly all sold out when i ordered


yes 2-2-2-5 is quite fast, and thats why im buying it for my next computer

it does 300mhz with relaxed timings 3-4-4-7 t2. i only need it to go around 270-280

usually dual channel = two slots of the same ram.

note the two blue slots and the two black slots. they go into those. some higher end motherboards (msi and asus brands) drop significantly with bad setups. ~300mbps bandwidth.

I think PolygoneUK is correct. The two identical sticks will register as dual channel if they are in the right slots and the alien stick will just add to the back end of it all. Take hydraviens advice and get sisoft sandra. That should put your mind at rest.