Dig Dat Ram

August 30, 2005 7:06 PM

Ugh, memory technologies change faster than Italian governments...

I'm considering upgrading my laptop, for which I just purchased 512mb of pc2100 (ddr266 ram). The new model comes with pc2700 (ddr333) ram. According to Crucial DDR memory is backwards compatible, but it doesn't mention forward-compatibility, i.e. whether I can use the older ram I bought in the newer sockets. Any help?

posted by Popular Ethics to computers & internet (6 answers total)

Yes, this has always worked fine for me. The only problem is that your ram will run at the speed of your slowest stick. So if you are adding a stick of ddr266 to a laptop that already holds a stick of ddr333, they will both run at ddr266 speed.

Also, check out specific brands for your laptop, I found that a cheaper brand did not function in a client's laptop. YMMV.
posted by meta87 at 8:18 PM on August 30, 2005

Thanks meta, that's what I was looking for.
posted by Popular Ethics at 9:56 PM on August 30, 2005

meta87 is wrong. ddr266 and ddr333 are mostly identical. It's just that ddr333 is higher quality and therefore able to run reliably at higher speeds. If you put ddr266 in your laptop, it will be run at 333MHz and there's a fair chance your system will be very unstable, if it boots at all.
posted by cillit bang at 11:58 PM on August 30, 2005

(I should mention that there's a possibility that your "DDR266" memory may turn out to be good enough quality to work at 333MHz and/or may actually be DDR333)
posted by cillit bang at 12:07 AM on August 31, 2005

huh. Thanks for the update CB. I suppose there wouldn't be any harm in trying the ram, but I'll watch for any trouble.
posted by Popular Ethics at 6:57 AM on August 31, 2005

You may be able to convince slower memory to run at higher clocks by relaxing memory timings. There should be somewhere in your BIOS you can set things like CAS latency and other timings; higher is slower but likely to be more reliable. YMMV; memtest86(+) should find any problems fairly quickly, but you might want to run it overnight before risking running an OS on potentially marginal memory.
posted by Freaky at 12:59 PM on August 31, 2005