A cooling block for cooling a heat-generating electronic component, comprising: a body having a thermal transfer surface on a lower side thereof configured to be in thermal contact with the heat-generating electronic component, the body defining a fluid conduit for circulating a cooling fluid therethrough, the fluid conduit having an inlet and an outlet for receiving and discharging the cooling fluid respectively; the fluid conduit having a plurality of channels (122 1, 122 2) extending from a first point to a second point along the fluid conduit such that, in use, the cooling fluid flows in parallel along the channels from the first point to the second point, each channel of the plurality of channels being defined between: first and second internal sidewalls (140, 142) defining a width (W1, W2) of the channel therebetween; and top and bottom walls (146, 144) extending between the first and second internal sidewalls, a height (H1, H2) of the channel being defined between the top and bottom walls, the bottom wall being closer to the thermal transfer surface in a height direction of the cooling block than the top wall, wherein: each channel of the plurality of channels is dimensioned to have either: a first dimensional configuration whereby the height of the channel has a first height value and the width of the channel has a first width value; or a second dimensional configuration whereby the height of the channel has a second height value and the width of the channel has a second width value, the first height value being greater than the second height value, the second width value being greater than the first width value; the plurality of channels includes at least one first channel having the first dimensional configuration and at least one second channel having the second dimensional configuration; and a thickness of a material of the body between the thermal transfer surface and any part of the at least one first channel is less than a thickness of the material of the body between the thermal transfer surface and any part of the at least one second channel. a body having a thermal transfer surface on a lower side thereof configured to be in thermal contact with the heat-generating electronic component, the body defining a fluid conduit for circulating a cooling fluid therethrough, the fluid conduit having an inlet and an outlet for receiving and discharging the cooling fluid respectively; the fluid conduit having a plurality of channels (122 1, 122 2) extending from a first point to a second point along the fluid conduit such that, in use, the cooling fluid flows in parallel along the channels from the first point to the second point, each channel of the plurality of channels being defined between: first and second internal sidewalls (140, 142) defining a width (W1, W2) of the channel therebetween; and top and bottom walls (146, 144) extending between the first and second internal sidewalls, a height (H1, H2) of the channel being defined between the top and bottom walls, the bottom wall being closer to the thermal transfer surface in a height direction of the cooling block than the top wall, first and second internal sidewalls (140, 142) defining a width (W1, W2) of the channel therebetween; and top and bottom walls (146, 144) extending between the first and second internal sidewalls, a height (H1, H2) of the channel being defined between the top and bottom walls, the bottom wall being closer to the thermal transfer surface in a height direction of the cooling block than the top wall, wherein: each channel of the plurality of channels is dimensioned to have either: a first dimensional configuration whereby the height of the channel has a first height value and the width of the channel has a first width value; or a second dimensional configuration whereby the height of the channel has a second height value and the width of the channel has a second width value, the first height value being greater than the second height value, the second width value being greater than the first width value; a first dimensional configuration whereby the height of the channel has a first height value and the width of the channel has a first width value; or a second dimensional configuration whereby the height of the channel has a second height value and the width of the channel has a second width value, the first height value being greater than the second height value, the second width value being greater than the first width value; the plurality of channels includes at least one first channel having the first dimensional configuration and at least one second channel having the second dimensional configuration; and a thickness of a material of the body between the thermal transfer surface and any part of the at least one first channel is less than a thickness of the material of the body between the thermal transfer surface and any part of the at least one second channel.