RAM running in "Virtual Single-Channel" mode

[TheSambassador]

Hey all,

I've got a quick question regarding RAM speed and it's effect on game performance.

I've got 2 gb of PC3200 (DDR400). It's in the configuration of 2x512 chips of Corsair, with a CAS of 2.5, and then 2x512 chips of Patriot, with a CAS of 2.0. I'm running these on an ASUS P4P800SE Motherboard with a Intel Pentium 4 3.2 ghz processor with an 800mhz FSB.

When my computer boots up though, it proclaims "DDR Frequency: 266mhz, operating in Single-Channel mode or Virtual Single-Channel mode".

Now I'm guessing that that display should either be displaying 400mhz or 800mhz, right? Can you not mix latencies like that? Each DDR memory bank channel is populated with its identical counter-part...

Now say that these two RAM types ARE incompatible for Dual-channel mode. Would it be an advantage, strictly with games in mind, to remove a gig and run it so that it IS running in Dual-channel, or should I keep it with 2gb even with the slower frequency?

Thanks!

Sam

 

[Mondoman]

...
When my computer boots up though, it proclaims "DDR Frequency: 266mhz, operating in Single-Channel mode or Virtual Single-Channel mode".

Now I'm guessing that that display should either be displaying 400mhz or 800mhz, right?

Not necessarily. The settings advertised for RAM are normally different from the more conservative settings programmed into a RAM DIMM's SPD for "auto" speed/latency selection. See this post for more details: http://forumz.tomshardware.com/hardware/modules.php?name=Forums&file=viewtopic&p=1249881#1249881

Another possibility is that your MB cannot support 4 DIMMs installed at its maximum DDR-400 speed, and is automatically dropping the speed.

Since it seems you may be trying a number of manual memory settings, first get memtest86+ (freely downloadable as a floppy or CD bootable image file ready to burn) so you can run it after changing settings to test that your memory is working correctly.

... Can you not mix latencies like that? Each DDR memory bank channel is populated with its identical counter-part...

First, the manuals are sometimes wrong in their description of how modules need to be arranged for dual-channel mode. Thus, I would install only 2 identical modules, trying all 6 possible slot combinations, to see which (if any) work in dual-channel mode.
Second, you have an older MB and chipset design, so it is likely has stricter requirements for the memory modules to work in dual-channel mode. In any case, using Win, you're better off with 2GB total RAM than 1GB, even if you have to go to single channel mode, as the RAM is much faster than virtual memory swapped to a hard drive.

 

[TheSambassador]

Thanks Mondoman! Your post was definitely very helpful.

When I do use just 2 memory sticks, it does say "DDR frequency 400mhz, Dual-channel mode." So at the very least... shouldn't my ram, with all 4 sticks in there, be running at 400mhz single-channel mode? Just seems like that's how it should be.

I also tried mixing the possible combinations of the 4 ram chips in all 4 of the slots, all of them resulted in the 266mhz virtual single channel mode.

Game-wise though, would it be worth just getting 2 1gb chips to populate the ram slots so that I could run dual-channel? Would sticking with just 1gb have an increase on my performance, as long as I didn't overflow into the virtual memory?

Thanks

 

[Mondoman]

... So at the very least... shouldn't my ram, with all 4 sticks in there, be running at 400mhz single-channel mode?

Best case would be 4 sticks at 400MHz in dual-channel, but in real life it depends on the quality of your MB and the quality of the RAM DIMMs.

...
Game-wise though, would it be worth just getting 2 1gb chips to populate the ram slots so that I could run dual-channel? Would sticking with just 1gb have an increase on my performance, as long as I didn't overflow into the virtual memory?

I wouldn't expect a noticeable difference, but to know for sure you'd have to try it out on your system with your games the way you play them. Normally, memory throughput is not a big factor in game speed. The biggies are (1) graphics card (by far!) and (2) CPU core speed.

 

[wigginender]

I just noticed that I was getting the same exact message with my P4P800SE and on examining the MB, I discovered I has installed my two sticks of DDR RAM in the wrong banks; switching the sticks to the blue slots (A1 + B1) as described in the manual solved the problem.

 

[SpinachEater]

Thanks Mondoman! Your post was definitely very helpful.

When I do use just 2 memory sticks, it does say "DDR frequency 400mhz, Dual-channel mode."

MrsBytch, he has them in the correct banks...perhaps you skipped over the posts...it is clear that he knows how to set up dual channel.

Did you test out each pair that you had or just check that dual channel was working? It sounds like there is a DDR 266 module in your mix but if you got DDR 400 for each set then that isn't what is going on.

When you tested the dual channel mode, did you only use slots 1 and 3 for example? Did you check if 2 and 4 allowed dual channel too?

Did you also check each individual RAM module to see if you get DDR 400 from each one?

 

[Xtreeme]

A few of these droped Dual Channel with 4 dims used. If I remember right (was while ago LOL). I think it has to do with the NB chip in the early Dual Channel days. Dont forget to, your mixing timings so that maybe the speed drop. Many more important timings then just cas. Id suggest as another poster did. Run everest, go to motherboard then SPD. Right down the ram timings for each ram set. Then go to bios and set the SLOWEST timings of the two for all. This will try to balance them somewhat. Run memtest86 so you know its stable. Now it may get 333mhz 400mhz was always a gamble with 4 sticks on the older platforms. NB just couldnt do it on many.

Btw, I have a Asus A7n8X deluxe here that ran 3 sticks in dual channel. The 3rd bank ran on channel 1. So odd number DID support Dual Channel. It just depends on the North Bridge and mainboard layout.