Member Avatar for graybeard47

I have an old emachine T2542 with a Celeron 2.5 Processor 400 MHZ FSB. The spec sheet states that it uses PC 2100 memory but when I ran a Aida32 System progam, it stated that PC 2700 ram was installed. Three years ago I went ahead and installed more 2700 ram and everything is well.

As the motherboard will accept up to 2GB, I'm looking at adding more. However, I began thinking that since PC2100 was specified, that my purchase should be the 2100 to boost performance.

Our other desktops are more current brand names, but this unit is used on occassion by others.

Your thoughts?

Your help is greatly appreciated.

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  • Latest Post Latest Post by sittas87

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Replies from , , and hit the usual tradeoffs: follow the motherboard maker for guaranteed compatibility, or match what has already been running successfully. Both are valid. The important technical point is that the memory controller and the modules themselves determine the actual operating rate; modules rated faster than the system will typically run at the slower supported rate rather than forcing the whole system to run faster.

Practical compatibility notes that are not always obvious: the SPD data on each module tells the board how to set speed and timings; mixing modules with different voltages, ECC vs non‑ECC, registered vs unbuffered, or different densities/rank layouts can cause instability or disable multi‑channel modes. Timings and voltage often matter more for stability than the peak frequency on the sticker. Heat differences between modules are usually minor in a desktop; stability is the real concern.

Checklist to decide and to act

  • Identify existing sticks (use a tool like CPU‑Z to read SPD and part numbers).
  • Check the motherboard support/QVL and the vendor's memory guidance.
  • Prefer identical modules (same part number/voltage/timings/density) or buy a matched kit for multi‑channel.
  • Avoid mixing ECC/registered with non‑ECC/unbuffered.
  • Update the BIOS if updates note improved memory compatibility.
  • After fitting new modules, run an extended memory test (for example, MemTest86) to confirm stability.

If the currently installed modules have been reliable, adding identical modules is the lowest‑risk option. If guaranteed compatibility is required, buy to the motherboard/vendor recommendations and keep receipts for returns. For SPD basics see Serial Presence Detect (SPD). For inspection and testing tools see CPU‑Z and MemTest86.

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Member Avatar for Chromium

stick with the 2100, i can't remember what the rule is but the mhz of the ram shouldn't be higher than the cpu FSB, can't tell ya for sure. I do know it runs hotter, at least in my laptop (which is 533mhz i think) i put in 6-something and it runs about 5 degrees f Hotter...i dunno :P

Member Avatar for coolraj003

But if you already have a 2700 working on it for a while now i would assume yuo should be ok getting more 2700 to add to it. You know for a fact that it works so i dont see any issues there. Obviously there could be issues if you mix up 2700 and 2100 sticks as ideally you should have only one type of ram to work on.

Raj

Member Avatar for sittas87

sometimes user manuals states recommended ram but that doesnt mean that, thats your limitation.If pc2700 is what youve been using and your the machine likes it than you can remain with pc2700

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