Unlike desktop motherboards, 99.9% of the time laptop motherboards are not interchangeable. Most laptop motherboards will only work with a select number of laptop models. To complicate the matter further, some models may come different motherboards, even if the model numbers are exactly the same. To that end, the only correct way to replace your laptop motherboard is to use the same exact part number that is on the original motherboard. Below are some examples of what a motherboard part number will look like. Some times all you need to do is check around the memory slot; other times the entire board needs to be taken out of the motherboard chassis; this depends on the model that you have.
HP Motherboards



Most HP motherboards have the part number on the bottom of the laptop, printed on a white label located either behind the memory slot, or on the memory slot it self. Most of the labels will say "REPLACE WITH HP SPARE". The part number consists of 6 numerical digits followed by a dash and 3 more numerical digits (usually 001, ex: 434660-001, 571186-001, 447805-001...). Some older Compaq models use part numbers starting with an F (ex: F1580-69001, F2157-60937)
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Toshiba Motherboards

Toshiba motherboard part numbers are sometimes difficult to find; they can be on a white part of the motherboard, or imprinted into the circuit board itself. However, they are easily recognizable: The part number will start with one of the following letters: A, H, K, P, or V. This is the only non-numerical part of the part number and is followed by zeros (any where from 3 to 7 zeros, ex: A00000710, K000811030, V000051700...).
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Dell Motherboards



Dell motherboards usually have the part number near the memory slot on a white label. They are usually nested inside a long sequence broken up by dashes. The actual part number in this sequence is usually the second part (after the first dash); it will usually start with a zero (although the zero is usually left out of the part number) and contain at least one non-numeric character in the beginning (ex: F5236, RJ272, W0938)
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Sony Motherboards

Sony motherboards usually have the part number near the memory slot on a white label. They usually start and and with an A and contain 6 to 7 numeric characters, sometimes separated by dashes (ex: A1211450A, A1175826A, A-1199-190-A, A-1143-861-A)
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IBM Motherboards

IBM motherboards usually have the part number near the memory slot. Most of the time they are identified as FRU numbers. They consists of 2 numeric characters, followed by 1 non-numeric character, then followed by 4 more numeric numbers (ex: 39T5433, 91P7382, 44C3738, 42W7842...)


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