Dual Memory Question

[Wally's World]

A non-CM related techie question if you don't mind.

I currently have two 256MB PC2700 RAM chips with dual memory enabled in a Epox 8RDA+ motherboard with an Athlon 2800+ and a 6600GT with Windows XP. I have a chance to buy a 512MB PC3200 chip pretty darn cheap and was wondering if going from 512MB to 1 Gig RAM while losing dual memory is worth it?

From reading on the web, some say dual memory is worth it while others say it isn't. The 8RDA+ only has three RAM slots so it's either the two 256 chips and one 512 chip or else stay with the two 256 chips with dual memory enabled. I don't want to buy two 512 chips right now to enable dual memory (and remove the 256 chips) if dual memory isn't worth it.

Should I bump myself up to 1 gig of RAM (2 256's and 1 512) or stick with dual memory enabled at 512MB (2 256's)?

Any opinions would be greatly appreciated. Many thanks in advance.

[ February 23, 2006, 06:31 PM: Message edited by: Wally's World ]

[Hpt. Lisse]

As a rule, dual memory control improves memory performance by 5% to 7% (depending on the application.) But for winXP, the jump to 1 Gig (again, depending on the game) can help you quite a bit (esp. if you play FPS games.)

[Redwolf]

Do you have an Athlon XP 2800+ or an Athlon 64 2800+?

The performance improvement of dual-channel memory is for most real-world application at or even below 3%, for AMD64s with the integrated memory controller. It is certainly more important to get 1 GB RAM up.

I highly doubt you will find any interactive application where you can notice a slowdown when doing to single-channel RAM, but sure as hell you can see the 1 GB.

[Schrullenhaft]

I would agree with the others that the tradeoff of dual-channel for 1Gb of memory would be worth it. Some of the latest games seem to be 'requiring' 1Gb or more to perform optimally.

One other thing is that it may be possible to keep dual-channel mode with all three DIMM slots filled. As strange as that sounds, I've seen it happen - or at least the motherboard "claimed" to be working in dual-channel mode. You could fill slots 2 & 3 (the ones close to each other) with the two 256Mb DIMMs you have and then fill slot 1 with the 512Mb DIMM.

This article in digit life about nForce 2 chipsets gives a little more info on the issue. The specific text is:

It's also possible to use three modules, but remember that the dual-channel access can be set only for the memory size equal to the double size of the first module (which is installed into the slot of the lowest number), and if the size of the first module does not exceed the sum of the sizes of the second and third modules. Obviously, there are two most optimal cases: equal memory modules inserted into the first and second slots, or three modules, with the first one being equal to the sum of the other two modules.

The text seems a bit awkward, but it supports the idea that the two 256Mb DIMMs in one channel/bank (slots 2 & 3) and the 512Mb DIMM in the other channel/bank (slot 1) could potentially work (at the PC2700 speed and the timings of the slowest module). However there are other issues concerning the memory modules themselves that could prevent dual-channel from working.

Here's a forum that discusses dual-channel on the 8RDA+, which pretty much echoes what was said above and a pic at the bottom showing the slots for dual or single channel (in case I don't have the slot numbers correct).

[ February 24, 2006, 12:20 PM: Message edited by: Schrullenhaft ]

[Jack Carr]

I have an Athlon XP setup with Dual Channel enabled and I am using all three slots, so it is possible to do that. My motherboard is an ABIT and requires modules be placed in the first and third slots in order to enable dual-channel.

I think RedWolf and Schrullenhaft are right about dual channel's effect on speed. I used to have only two 512 modules in the first and second slots so that dual channel memory wasn't enabled. Now that it is enabled, I don't see a difference.

I would go for the extra memory and not worry about dual channel's pathetic performance increase.

[Wally's World]

Thanks very much for the replies.

Anyway I did go out buy the 512MB chip and installed it in my PC. However, it doesn't seem to want to work too well with either my motherboard or with my other RAM chips. By the way, My 2800+ is just an ordinary Athlon and not the 64.

I installed the new Mushkin 512MB PC3200 (3-3-3-8) in slot 2 to start with as slot 1 had my generic 256MB PC2700 chip and slot 3 had the Kingston 256MB PC2700 in which both ran in dual channel. My Epox 8RDA+ board immediately responded with a C1 error code to indicate bad memory. I then moved the 512 to slot 3 and move the Kingston to slot 2. The PC started find and reported 1 gig of RAM in dual channel mode(!). Windows XP loaded fine and when I ran CPU-Z, it also reported dual channel and 1 gig of RAM. However, the PC then started act funny (weird graphics started appearing) and would reboot itself. In other words, very unstable.

I then tried the 512 chip in slot 1 and the two 256 chips in slots 2 and 3. Again, a C1 bad memory error appeared. In fact, even when using the 512 chip by itself in slot 1, the memory error still occured. It appears that the only time the 512 chip will work is in slot 3 and then it's very unstable.

Could it be a bad 512 chip? Or maybe the board doesn't like having two PC2700 chips with a PC3200 chip? Or could it even be that Mushkin chips don't work well on my 8RDA+? On Epox's website, Mushkin is not listed as a perferred type of RAM to use with this board.

Should I return the PC3200 and get a Kingston 512MB PC2700 instead?

Forgive my ignorance of RAM and its workings. That is the one area I have problems understanding inside a PC.

Many thanks again for additional help.

[Redwolf]

Originally posted by Wally's World:

Should I return the PC3200 and get a Kingston 512MB PC2700 instead?

No, that is useless. You see neither Kingston nor Mushkin make their own chips and most don't make their own PCBs either.

You most likely have incomatible chips on the different modules. Buying new Kingston can get you the same chips as you have on the Mushkin memory, the chance is the same.

Please post photos that allow me to read the exact markings on the chips.

It might be possible to boot with two sticks, force the BIOS into some set of BIOS settings so that it does not autodetect settings. But I need the exact chip types beforehand.

[Wally's World]

Thanks everyone for all your advice.

The problem was the memory timings in my BIOS were set too low (Turbo 2-2-2-6). I instead bumped the timings up to just Aggressive (3-3-3-7) and I've had no problems since. Memtest ran fine. And I even still got the dual channel mode running on my motherboard with now three DIMM's (1-512, 2-256).

Thanks again!