Existing computer, adding memory, trouble!

ahartman

Member
Sep 3, 2002
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I built a computer a while ago - FX-55, Foxconn NF4UK8AA-8EKRS, 1G (2x512) Crucial RAM.

Everything works fine. I decided I wanted to add a 2nd gig of RAM, so I order the same item from Newegg as above.

Here's where things go south... I had expected to be able to run all 4 sticks (4x512) at once to get 2G. However, the computer isn't stable with all 4 sticks. The POST shows 2G of RAM running in single-channel mode (bad). By not stable, I get constant (but not consistent) reboots - sometimes during the boot, sometimes after the machine has been running for some random amount of time (never more than 5 mins or so, though).

Since I know the current two sticks work, I start swapping sticks - can't get the machine stable with any combination of old & new RAM. Machine is 100% stable with the old RAM.

So I start digging deeper. First thing I notice is the old ram is double-sided and the new RAM is single sided.

When I tried to boot with 1 old and 1 new stick, I found a line in the POST which said "DDR DIMM AT SLOTS 2 6 7". The same line using 2 old sticks shows "DDR DIMM AT SLOTS 2 3 6 7".

When I dug a little deeper, I think I figured out that my mobo, while having 4 slots, only supports 4 banks of RAM. Double-sided sticks take up 2 banks, so I think I understand why I can't run all 4 sticks at once (would require 6 banks, no?).

However, what baffles me is that I can't run the two new sticks by themselves - same instability. The POST shows 1G running in dual-channel mode (ok, good). It shows two slots of DDR DIMM (makes sense given they're single-sided).

My first thought tells me I have a stick of bad RAM, but this is the 2nd order of RAM from Newegg (first order showed same symptoms and were single-sided). I didn't figure out the single-sided vs. double-sided then, but the symptoms are the same, so I'm kind of doubtful I got two bad sets of RAM in a row.

Cliffs
Trying to add 2nd gig of RAM to current machine, new RAM is single-sided, old RAM is double-sided. Machine not stable with all 4 sticks, machine not stable with 2 new sticks, machine IS stable with just the old two sticks.

Thoughts? I'm 1 BIOS update behind and will flash it to the current version and try again (notes only say something about BIOS password).
 

myocardia

Diamond Member
Jun 21, 2003
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Okay, first of all, four sticks of RAM with an A64 is not a good thing, but it can be done, assuming you know what you're doing. First of all, you're gonna have to change your Command Rate to 2T, no ifs, ands, or buts about it. You're also most likely gonna have to raise your other RAM timings, especially Tras and Trp.

And since you're trying to mix dual sided and single sided sticks, IF it's even possible for them to work together, it will be with matched sets. That means that you're doing it backward. Put one single sided and one dual sided stick in each bank. You're gonna want to have 3 "sides" in each bank, NOT 4 in one bank, and 2 in the other. It still may not work, though; alot of that depends on the motherboard, not just which core your processor happens to have.
 

ahartman

Member
Sep 3, 2002
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I appreciate the reply.

I didn't realize running 4 sticks of ram with an Athlon 64 would be an issue - I haven't read about it anywhere before.

All the timings are set on Auto - maybe I'll play around with those to see what's up.

I am completely in the dark about matched pairs - on my mobo (Foxconn NF4UK8AA-8EKRS, noted above), slots 1 & 2 are together and slots 3 & 4 are together. It sounds like you're suggesting I put one double-sided stick and one single-sided stick in slots 1 & 2 and the same for slots 3 & 4. Counter-intuitive to me, but I'll give it a shot.

On a side note, I'm irritated that Newegg would sell double-sided and single-sided RAM under the same part number.

Any thoughts as to why the two single-sided sticks of RAM won't work by themselves? Again, my first thought was bad RAM, but this is the second set of RAM to behave like this - they simply won't work in any slots.