Answer five questions about your PC or laptop and get a plain verdict: what RAM generation, form factor, capacity and speed to buy.
Updated 11 Nov 2026 · 6 min read
Quick answer
Use the checker below: tell it your device type, motherboard/CPU generation and what you want to do. It applies the four compatibility rules — generation, form factor, capacity and speed — and tells you exactly what to buy. The full reasoning is in our compatibility checker guide.
RAM Compatibility Checker
Answer five questions about your PC or laptop and get a plain verdict: what RAM generation, form factor, capacity and speed to buy.
Contents
How to use this checker
- Pick desktop or laptop (this sets DIMM vs SO-DIMM).
- Select the memory generation your motherboard uses — check CPU-Z’s Memory tab if unsure. DDR generations are never interchangeable.
- Tell it your platform and goal; it returns a buy-spec you can paste into any store’s search.
That is the whole process: three steps, no account, no download. The checker asks for the facts that actually decide compatibility and nothing else. It does not ask for your budget or favourite brand, because neither changes whether a stick fits. What it returns is a buy-spec — a short description such as ‘DDR4, SO-DIMM, 2×16GB, 3200 MT/s’ — that you can paste into any shop’s search box and get matching results.
The four compatibility rules it applies
Every RAM purchase must pass four checks, and the checker applies them in the order that kills bad orders fastest. If any one fails, the stick will not work — there are no exceptions and no adapters that fix a wrong generation.
- Generation: DDR3, DDR4 and DDR5 have different pin counts and notch positions. A DDR4 desktop stick has 288 pins; DDR5 also has 288 pins but the notch sits elsewhere, so it will not seat. Laptop SO-DIMMs are 260 pins for DDR4 and 262 for DDR5.
- Form factor: desktops use DIMM, laptops use SO-DIMM. A desktop stick is about twice as long as a laptop stick and the slots are different sizes.
- Capacity: every CPU and motherboard has a maximum total memory and a maximum per slot. A stick larger than the per-slot limit is simply ignored by the machine.
- Speed: a stick faster than the platform supports will downclock and work; a stick slower than what is installed drags everything down to its speed. Speed is the only rule where ‘wrong’ still works — it just wastes money or performance.
Worked examples: what the checker recommends
Example 1 — gaming desktop, DDR4, 8GB installed. You tell the checker: desktop, DDR4, gaming, currently 1×8GB. It recommends a 2×16GB DDR4 kit at 3200 MT/s, replacing the existing stick. Why a pair rather than adding one 8GB stick? Because a matched pair guarantees dual channel and identical timings, and 32GB gives the machine room for modern games plus background apps.
Example 2 — office laptop, DDR4, 8GB soldered plus one free slot. The checker recommends a single 8GB DDR4 SO-DIMM at the same speed as the soldered memory, giving 16GB total in dual channel. Buying a 16GB stick instead would give 24GB in flex mode — also fine — but for office work the extra 8GB buys nothing, so the checker does not recommend spending on it.
Common mistakes the checker catches
The most common mistake is buying on headline speed alone. A kit sold as ‘3600MHz’ DDR4 may be JEDEC 2400 with an XMP profile; in a laptop with no XMP option it runs at 2400, and in a desktop it runs at 2400 until you enable XMP. The checker asks for your platform so its speed recommendation is one you will actually get, not one that needs a BIOS setting you may not have.
The second mistake is mixing generations: people with a DDR4 machine see a cheap DDR5 kit and assume memory is memory. It is not, and the checker blocks this at the generation question. The third is capacity: buying a single 32GB stick for a laptop whose CPU supports 16GB per slot. The machine will either ignore the stick or see only 16GB of it, and the buyer concludes the stick is faulty.
When the answer changes
The checker’s answer is tied to your machine, so it changes when the machine changes. A BIOS update can raise the supported speed or add support for larger sticks — laptop manufacturers do this regularly, so if the checker says your laptop caps at 16GB per slot, check for a BIOS update before treating that as final. A CPU upgrade changes the limits too, because the memory controller lives in the CPU.
Frequently asked questions
I don’t know my motherboard’s DDR generation. How do I find it?
Install CPU-Z and open the Memory tab — ‘Type’ shows DDR3, DDR4 or DDR5. Or check the stick label: DDR4 desktop sticks are 288-pin and usually marked PC4; DDR5 is marked PC5.
The checker says my speed will downclock. Is the kit wasted?
No — it will work perfectly at the lower speed. You only overpaid for headroom; enable XMP/EXPO if your board supports it to use the full rating.
Can the checker tell me the exact brand and model to buy?
It gives you a buy-spec — generation, form factor, capacity and speed — rather than one brand. Any reputable stick matching that spec will work; buy from a brand with a lifetime warranty and a good returns policy.
Does the checker work for servers or ECC memory?
No. It covers standard desktop and laptop memory (unbuffered, non-ECC). Servers use registered or ECC memory with different rules — see our guide to ECC vs non-ECC RAM.
What if my laptop’s RAM is soldered?
Then no checker can help: soldered memory cannot be upgraded at any price. The checker will tell you the machine is not upgradeable, and your options are to live with the installed capacity or replace the laptop.