Tower heatsinks and VRM cooling: real issue?

ekerazha · Post by **ekerazha** » Tue Oct 28, 2008 1:15 am

I've read here: http://www.silentpcreview.com/article30-page1.html

[...]

Tall tower (or high rise) heatsinks with fans that blow air parallel to the motherboard rather than down at it are more likely to cause VRM component cooling problems â€” even when the fan is not run at minimal speed, bcause the airflow is sometimes blocked by the fins from reaching the sufrace of the motherboard. When the fans on such heatsinks are slowed to minimum speed, VRM cooling can suffer quite a bit.

[...]

So, having read this, is a top-down cooler (like the Noctua) a best choice over a tower heatsink? How do you care the VRM cooling using a tower heatsink?

Thank you.

FartingBob · Post by **FartingBob** » Tue Oct 28, 2008 2:02 am

Most new boards now have adequate cooling on the VRM's as they anticipate many users wont be using top down coolers, so it shouldnt be an issue unless you have an old board with no heatsink on any of them.

ekerazha · Post by **ekerazha** » Tue Oct 28, 2008 2:09 am

Because I've also seen recent motherboards (ex. Asus X48 based) that already use heatsinks but also include a fan to use when the cpu is liquid-cooled because using liquid cooling you wouldn't have airflow on the MB heatsinks.

FartingBob · Post by **FartingBob** » Tue Oct 28, 2008 4:43 am

ekerazha wrote:Because I've also seen recent motherboards (ex. Asus X48 based) that already use heatsinks but also include a fan to use when the cpu is liquid-cooled because using liquid cooling you wouldn't have airflow on the MB heatsinks.

Thats more of a tool for overclockers (liquid cooling tends to go hand in hand with overclocking still, and the x48's are made for big OC's). If your overclocking your board heavily (increasing voltages especially) then yes you probably would want some extra air being pushed onto them, but under normal conditions the heatsinks are plenty fine.

thejamppa · Post by **thejamppa** » Tue Oct 28, 2008 7:49 am

and in mainstream boards you don't have heatsinks on mainboard and they are perfectly fine in regular use no matter what cooling you have. Single case fan usually makes enough air flow thru-out the case.

Issue's might come in poorly ventilated cases with overclocking. But generally VRMS cooling is not an issue.

Topdown cooling VRMS and mosfets is yes true, but basicly that is just advertising point without real concern for regular user.

pony-tail · Post by **pony-tail** » Wed Oct 29, 2008 12:30 am

Yes it is a very real issue ! For some motherboards ( M3N32SLI deluxe from Asus is such a board ) but for most boards you will get away with it . You would have to evaluate the issue on a board to board basis . Even the choice of case and case fans has an effect . Some boards that have onboard graphics can have problems too . But with that said most of the worst offenders are nVidia SLI chipsets - which most (but not all ) silent enthusiasts would avoid .
From personal experience - I killed the northbridge on an M3N32SLI mobo using a Thermalright HR01 plus with a 500rpm fan . it got hot enough to discolour the back side of the mobo . So if you are going to do things like that , Plan your build and choose your components carefully after you do your research .
Edited for footnote - I live in Australia where daytime temps can be in the high30c to low 40c range so what may fry in my area may be fine in yours ( unless global warming has pushed temps in Finland ,Norway ,Canada and similar places up to those temps - although I think that is a few years off yet !

thejamppa · Post by **thejamppa** » Wed Oct 29, 2008 7:33 am

Well, nVidia chipsets have generally always been burning hot ones and their motherboards have been more or less hot ones for me.

I've had nForce 2 Ulta, nForce 4 Ultra Sli, nVidia 430 MCP and GeFOrce 6100 Motherboards which all of them have had very, very hot heatsinks. But generally VRMs are not really an issue, unless there are some motherboards which design is pis-poor job or if you live in very hot climate as Pony-Tail does.

But if you're affraid about VRM cooling, there plenty good Heatsinks in top-down category: Asus Triton 75, Thermalright SI-128SE, Noctua NH12C, Scythe Zipang, Xigmatek HDT-S1284 which all provide good to excellent CPU cooling.

ntavlas · Post by **ntavlas** » Wed Oct 29, 2008 12:55 pm

It also depends on the cpu used and number of power phases/mosfets. A six phase 18 mosfet design feeding an idling dual core is hardly stressed. On the other hand, 4 phases with 12 mosfets feeding a quad core at load will need the extra cooling.

Ditto with ambient temps like pony tail said. +20 degrees ambient can make the difference between running within spec and premature failure.

If you use a tower cooler you could remove the i/o shield to get some fresh air enter right above the vrms.

batka · Post by **batka** » Sat Feb 14, 2009 10:08 pm

Hi All,

If I would use a Ninja 2 passively but with decent airflow in the case, will be the northbridge temperature cooled down properly?

I'm little worried about that in case there is only airflow parallel with the motherboard, is it enough for the northbridge to cool down?

I plan to use an Asus P4P800-E Deluxe board (i865 chipset) in an Antec Solo, and an Asus P5Q-E board (P45 chipset) in an Asus TA-98 chassis. These boards northbridges will be cool when using a Ninja 2?

Thanks!

Lawrence Lee · Post by **Lawrence Lee** » Sun Feb 15, 2009 2:13 am

batka wrote: If I would use a Ninja 2 passively but with decent airflow in the case, will be the northbridge temperature cooled down properly?

Unless you're using a very high power chip (e.g. Pentium D), it should not be an issue. That's been my experience.

batka · Post by **batka** » Sun Feb 15, 2009 6:14 am

Lawrence Lee wrote:Unless you're using a very high power chip (e.g. Pentium D), it should not be an issue. That's been my experience.

I'll using a P4 Northwood 2.4 GHz in the Asus P4P800-E Deluxe (i865).
I'll using maybe a E8200 proc in the Asus P5Q-E (P45).

I just have thought that maybe it's worth to try a Zalman FB-123 fan bracket console with a slow fan above the northbridge, but I need to measure and calculate whether it will be enough space next to the ninja 2. I think they are cannot be together but I need to check.

batka · Post by **batka** » Wed May 05, 2010 2:32 am

Hi Again!

I make a bump , just for verification, on this thread, on the same question.

I (still) plan using Ninja 2 to cool down a P4 Northwood 2.4C GHz 800 Mhz FSB (TDP=65 W ) on motherboard Asus P4P800-E Deluxe (i865).

The motherboard is this:

My question: if there is only airflow parallel with the motherboard, is it enough for the northbridge (can be seen on above picture) to cool down, and the capacitors next to the socket won't be damaged by heat?
I guess the Northwood 65 W with Ninja 2 should drive away the heat properly, but just what are your opinions?

Thanks
GyÃ¶rgy

marcus_helsinki · Post by **marcus_helsinki** » Tue Aug 17, 2010 9:33 am

I don't know the components, but if I speak what I noticed when I tested cooling of components without heatsinks (other that these), the only that worked was a 120 mm Nexus at 12V very near blowing directly or at leat at an angle of 45 degrees at the components to be cooled.
if the flow is parallel, the height level of other components creates some protection from flow. In theory, in parallel viscous flow, the flow velocity (and heat transfer) near a rough surface gets very low. The roughness of the surface (motherboard) is caused by other components.
When the flow is at the components, the strong turbulence gets near the surface and transports the hot air effectively away.

This is the same thing, why fans should blow air through heatsinks, not suck air from them; when blowing at, the turbulence is much higher. When air is sucked from a heatsink, layers of very slow flowing air are created on the fins.