Ganged vs. Unganged, the rematch!!

H

Hexen525

Limp Gawd
Joined
Feb 20, 2007
Messages
186
Evening all.

Not sure how many times this has been covered, but I am thinking I have a new slant on it. Check the sig for system specs. I am running an AMD FX-8150. Currently running 4x 2GB RAM. Looking to upgrade to either 16GB or <gasp> 32GB (cheap enough atm).

Now, I was always told on forums and such that unganged unlocked the RAM to single channel allowing for each core to have it's own stick of RAM. So how does that work with an 8-core CPU? My mobo only holds 4 sticks of RAM. Would I be better off with 2x sticks or 4x sticks? I am running an OC atm. I know I've had issues in the past running 4 sticks of RAM and OCing. Was hoping to go back to 2 sticks. But would rather sacrifice a couple hundred MHz for twice as much RAM. Ideas?

Thanx all.
 
i think he was looking for something a little less technical than that article. also i don't want to read 10 pages to get" I THINK "unganged is the preferred method
 
Well I prefer Ganged mode personally and have even gone as far as returning a motherboard that didn't work in ganged mode. I feel like GTAIV runs less glitchy in ganged mode due to the game wanting to use such a large hunk of RAM.
 
gentle said:
i think he was looking for something a little less technical than that article. also i don't want to read 10 pages to get" I THINK "unganged is the preferred method
Click to expand...

Which is why I only linked the conclusion page, not the start page. If he wanted to delve into it as to why, then he could have read the other pages.

Besides, the reviewer was pretty specific about which cases ganged and unganged mode worked better in.
 
The summary works fine. From TFA:

"while the ganged mode is faster than unganged one in single-thread memory read access, it is top-capped by the per-core L3 bandwidth speed and so, in the end, even in single-thread application the unganged mode is not far behind
"
Relevance? The BD CPU has been known to have relatively slow L3 cache.
 
Well, my question actually pertains to an 8-core CPU and whether or not to use 4 sticks over 2 sticks of RAM. I know the benchmarks of Ganged vs. Unganged on the Phenom II platform. My question is how does it affect having more cores...and possibly fewer sticks of RAM.
 
The difference is making the CPU see two 64-bit channels or one 128-bit channel. It doesn't necessarily give each core its own channel. It really has nothing to do with how many cores you have.

No matter how many stick you use, there are only two channels. 2 sticks or 4 doesn't matter much. The memory controller MAY be able to interleave some reads and writes across 2 sticks on a single channel, but in the real world 1 stick per channel vs 2 per channel doesn't see much of a speed difference. Generally you can clock the memory higher speed if you only have 1 stick per channel, and the benefit of more clockspeed with 1 stick per channel trumps any benefit you may get from interleaving.
 
Its well known by now that unganged generally favors multithreaded appz while ganged is better for single threaded.
 
Thanx. That's what I was wondering. My last setup was a Phenom II 965 quadcore with 4 sticks of RAM. Never thought about it. Well, I want more RAM (8GB is not enough oddly) and now questions came up in my mind. Rather do 2x 8GB sticks than 4x 4GB sticks.
 
Solomutt said:
The summary works fine. From TFA:

"while the ganged mode is faster than unganged one in single-thread memory read access, it is top-capped by the per-core L3 bandwidth speed and so, in the end, even in single-thread application the unganged mode is not far behind
"
Relevance? The BD CPU has been known to have relatively slow L3 cache.
Click to expand...

So for someone like me who's CPU does not contain any L3 cache at all does that mean i'd benefit from unganged mode way more than someone with a Phenom or Faildozer??
 
Hexen525 said:
Thanx. That's what I was wondering. My last setup was a Phenom II 965 quadcore with 4 sticks of RAM. Never thought about it. Well, I want more RAM (8GB is not enough oddly) and now questions came up in my mind. Rather do 2x 8GB sticks than 4x 4GB sticks.
Click to expand...

Although there might be some performance benefit, 8gb sticks have lower max clock speeds at the moment. In your case, it would be better to get a 4x4gb 1600 mhz set than a 2x8gb 1333 mhz set, especially when the 2x8gb set costs almost twice as much as 4x4gb in some cases. This wouldn't hold true if we were talking about 2gb vs 4gb sticks, since 4gb sticks match 2gb sticks in speed.

And yeah, the number of RAM sticks is pretty much transparent to the CPU core. What is important is the number of channels.
 
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