RAM upgrade question

[bighoo93]

So, my old build (http://forums.mysuperpc.com/showthread.php?1550-Success!-With-a-few-temporary-snags), now in use by the rest of the family, is still a little sluggish. A week ago MicroCenter had the i7-2600k processor for $200, and I almost pulled the trigger to upgrade the whole system...but too late. Anyway, I was just going to double the RAM to 4 GB, because it seems like that might be a limiting factor right now (I am running 32 bit Vista, so I understand that I won't actually see the full 4 GB). When I went back to find the same exact RAM that I had already installed, I found that it is has been discontinued. However, I found what appears to be the successor product with the same specs (as far as I can tell)

Original RAM: CORSAIR XMS2 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model TWIN2X2048-6400C4 (http://www.newegg.com/Product/Product.aspx?Item=N82E16820145034)
Successor RAM: CORSAIR XMS2 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model TWIN2X2048-6400 (http://www.newegg.com/Product/Product.aspx?Item=N82E16820145590)

Should I be OK to add this new RAM to the old one? I wanted to put the exact same product in, so I looked to the same manufacturer, but I am concerned that there may be issues. The motherboard is also discontinued.

[zburns]

You will see 3.6 GB, I think that is the number. I compared the two using the Newegg specs. The only diff is latency and voltage. The 'old' has the following: Cas Latency 4: Timing of 4-4-4-12 and voltage of 2.1 volts. The 'new' has the following: Cas Latency 5: Timing 5-5-5-18 and voltage of 1.9 volts.

Because the cat numbers are essentially the same, you would think you could use the new items along with the old. However, your BIOS will probably only allow you to set one voltage for all the RAM. You have to leave the voltage, I assume, at 2.1 volts for the 'old'.
That would mean you would be forced to run the new at 2.1 rather than 1.9. While this is not a huge deviation, it is greater than the spec for the new. The timing on the new is 'slower' for the new compared to the old; whether the cpu thru the mobo chipset for controlling the cpu will via software adjust to force all RAM to run at the slower of the timings, I do not know.

The best 'route' is to call Corsair Tech Support. Explain the 'similar' cat #s; more importantly, ask if the voltage on the new can be run at 2.1 instead of 1.9, and ask if the timing difference between the old and the new will be a problem? BUT -- if you do call, you have to ask the rep several times 'if he/she is 'sure' of the answers given -- you cannot accept 'guesswork' -- the answers have to be certain. I generally would repeat my questions several different ways, etc.. Most tech support folks are going to be specific in their answers; if they do not know, I assume they will say that, etc..

Because the cat #s are essentially the same, you would assume the new can replace the old, but in your case, you will have to fill two slots of your dual channel with the old and the other two slots with the new -- and the slots are separated into two separate channels. But because the cat numbers are the same, it is reasonable to assume you can mix them; however, it is just as reasonable to assume that these new 'birds' are meant to replace all the old ones 100 % and at the same time!

The tech support rep should have a 'data sheet' with the answers to the questions I mentioned above -- the questions are the obvious ones to ask. If the tech rep has nothing in writing to 'support' these (your) questions, I think you can assume you cannot mix them! But if you cannot mix them, I cannot understand the 'same' cat #s, except in the case where the similar cat #s are meant for the newer RAM to be a complete 100% replacement for the older RAM!

So, you may (1) mix them in separate channels or (2) they are meant as 100% replacement for all the older RAM -- this is what I am saying -- but you have to get Corsair to tell you this!! The spec differences may require you to 100 % replace them!

[bighoo93]

You will see 3.6 GB, I think that is the number. I compared the two using the Newegg specs. The only diff is latency and voltage. The 'old' has the following: Cas Latency 4: Timing of 4-4-4-12 and voltage of 2.1 volts. The 'new' has the following: Cas Latency 5: Timing 5-5-5-18 and voltage of 1.9 volts.

Thanks for your reply. I saw that, but the "Details" tab appears to be misleading (or at least confusing). If you look at the "Overview" tab, you see that you can "achieve" the 4-4-4-12 with overclocking, but the standard appears to be 5-5-5-18.

Corsair's XMS (Xtreme Memory Speed) memory has long been popular among enthusiasts. Corsair has many such kits, and each is regarded as some of the best available in its category. With 2GB (2 x 1 GB) of memory in dual channel configuration running at 800MHZ speed, this CORSAIR XMS 2GB DDR2 SDRAM System Memory, offers targeted low latencies of 5-5-5-18 at JEDEC standard speeds, overclockable to 4-4-4-12, and it's been certified as “SLI Ready”, giving you some screaming data transfer rates and exquisite renderings.

I don't know about the voltage, though. Your advice to call Corsair is probably the right move. If I need to take out the existing 2 GB RAM and replace it with 4 GB new, that will be troubling and probably not worth the expense since I will probably try to upgrade the system altogether at some point.

UPDATE: Actually, I see that I could buy a 4 GB G.Skill kit (http://www.newegg.com/Product/Product.aspx?Item=N82E16820231122) for only $20 more, so maybe it is a bit of over-reaction to throw in the towel on this.

[zburns]

Your statement above
Corsair's XMS (Xtreme Memory Speed) memory has long been popular among enthusiasts. Corsair is for the original RAM, not the 'new' RAM.

[bighoo93]

Your statement above is for the original RAM, not the 'new' RAM.

It is quoted from the Overview tab of the original RAM (http://www.newegg.com/Product/Product.aspx?Item=N82E16820145034) (i.e., what is currently installed in my system).

No matter. I am going to buy the G.Skill 4 GB kit and not mess around with this. It is an extra $20, but worth avoiding the bother. Maybe I can get a few bucks for the original RAM on eBay or something.

[RickyTick]

I wouldn't use 2 ram sticks that have different voltage requirements. I think I would go with replacing all the ram with the new G.Skill kit.

[bighoo93]

Thank you both for your responses. I ordered the new RAM kit and will just trade out the old.

[bighoo93]

BTW, I installed the new RAM and it really works great. The system recognizes 3.6 GB, just as you said.

Also, I made a second page file on the secondary drive, and this may have helped with performance as well.