3 DIMMs don't work?

[skool h8r]

Hi all,
i received a 512mb Corsair XMS DIMM today. Ordered off ebay for £38 delivered. I've now got a problem. I've got 2 x 512 already in dual channel, but this one won't seem to work with them. I've tried it on it's own and with each of the other 2 modules (all 3 are identical) and it works fine. But i can't get all 3 to work together. I've even tried at stock settings and it doesn't work! Anyone got any idea what's wrong or how to fix it?

Is this just "one of those things, or is there a way to get them working together? Or do i need to buy another module to make up the full 4 DIMM's?

Thanks,
Scott.

[danrok]

An even number of sticks are required for dual-channel, i.e. 2 or 4.

Otherwise, you might want to try and run the 3 of them as single-channel.

[skool h8r]

i don't mind running single-channel, and my motherboard automatically sets it as the required mode. However, i simply can't do anything. It either crashes before POST, so i then lower my OC. It sometimes gets to windows boot up and crashes so i lower my OC a bit more. Then it sometimes gets to Windows and crashes after a few minutes after which time, i'm almost back at stock.

By crash, i mean automatically restarts or blue-screens. I didn't think there'd be such a problem with it. It detects ok as long as my OC isn't too high (if it is too high, then it only detects 512mb).

[cloasters]

Aah, the empty promise of four DIMM slots. Ya can't count on any m'board running more than two of the pesky buggers. Buy two and buy 'em big.

[danrok]

The A64 memory controller is fussy. Multiple modules need to be factory matched for good results. Otherwise, it will be hit and miss.

The current ideal is to have 2 x 1GB matched modules.

[MONKEYMAN]

you 520MHz speed at a 166 divider could be the problem,...this would make a running speed of 432MHZ, your sticks are rated at 400MHz

[skool h8r]

I think i've discovered the problem. The dual-channel i already had were version 5.2. The new one i have is version 2.2.

[Favu]

That must suck I'm no A64 expert - how much of a performance boost is had from running in dual channel? And will it out weigh the extra 512Mb ?

[skool h8r]

Well at the moment, i've gone back down to stock CPU and Auto DIMM divider and there's not much of a difference. The new dimm doesn't support 133mhz divider according to CPUZ 1.35. Not too bad i know.

I've got all 3 running and it's quite fast, probably because my timings are a bit tighter. It is in single-channel though at 64-bit as opposed to 128-bit dual-channel though. The seller did have another for sale so i presume thet were a matched pair at one time. I could do with 2Gb since many of the new games i'll be buying soon will need the extra. Crysis springs to mind immediately. I am considering using 512mb of system memory dedicated to PCI textures. Maybe i'll be able to play Q4 on ultra-high

But yes, the extra 512, even though i've got no OC, there's no slowdown so i'd rather have the memory.

And if you're wondering why my post is so confusing, i've just about got over a stomach bug i've had for the past 2 days.

[skool h8r]

Oh yeah, it looks like it's running at 166 rather than 200.

[Favu]

Ouch, that must be quite a big performance hit, going from DDR520 dual channel to DDR333 single channel.

[skool h8r]

I'm not really sure what i prefer; 1.5gb of low-speed, good timing, single-channel, 64-bit, or 1Gb of high speed, slightly-worse timing, dual-channel 128-bit.

Maybe i oculd sell these 3 modules and put a bit more money towards 2 x 1Gb. Think i'll go back to a gig for now. I have asked the seller if i can return them. He says it's fine but minus the ebay costs. Maybe it's not such a bad idea.

[skool h8r]

Ok, i did try earlier, and i could run Q4 in ultra-high with only slight hiccups. But i've discovered that the only difference between high and ultra-high is that ultra-high uses uncompressed textures to "save loading times". Anywho, i'm gonna be returning the module since i can get DDR556 out of this gig rather than stock at 166 single-channel. I think i'll put the money i get back towards another gig. At the moment, getting another gig of dual-channel exactly the same is like rocking-horse crap

But for once, OCUK are the cheapest place to buy memory from!

[danrok]

Try to get a pair of matched 1GB sticks, prices are falling all the time. Even the cheapest 2x 1GB option will be better than 4 x 512MB.

[skool h8r]

If i had £200, i would. I'm not going to put OcUK Value in this rig. It may be the last time i buy something this "important" from ebay (only thing i will probably get from there is a dual-core since they're so difficult to find anywhere else).

[danrok]

The point is, you can't expect much in the way of overclocking if you put 4 x 512MB sticks in to an A64 system, regardless of how much they cost. The memory controller is very fussy. Same goes for tight timings.

There's an element of luck here, but my money would go on 2 sticks of "value" RAM being better than 4 sticks of premium RAM.