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Discussion Starter #1
My system:

Fx 8350 @ 4.8ghz
R9 290
16gb g-skill Ares 1600mhz cl9 ddr3.

This system is cca. 5 years old, but since I don't need anything better yet, I have recently decided that I want to make a complete overhaul with custom water cooling. It was a big pain to find a suitable waterblock for this mobo, but I've finally found a watercool heatkiller (which had to be modified to fit formula-z). Now the main problem that I have are mosfets on the back of the board. Those were previously passive cooled by two very thin metal backplates (2mm height). Those 2 backplates also served as a mounting mechanism for the front vrm heatsink.

I would otherwise just keep the same mounting mechanism if that would be possible, but unfortunately it is not. The watercool block only has 3 mounting holes (instead of default 4). If a want to re-attach the default backplates, one of the backplate standoffs gets in the way of watercool block, where there is no mounting hole.

So there is no way for me to re-attach those backplates. I also don't want to leave those back mosfets with no passive cooling, so I was thinking about just putting some very thin heatsinks on them. For illustration purposes, I have some Akasa gpu ram heatsinks, which are 4mm tall. Now If I attach them to back mosfets, they would be touching the back of the case on the upper mosfet part. I'm afraid that could short something out or be bad in general.

Also I've read that those Akasa are not universal heatsinks, they should only be suitable for gpu ram. I have the dimensions needed for those 2 mosfet strips, I just need to find a suitable very low profile universal heatsinks with double sided thin thermal pads, so I can just glue them on. Matter of fact, the longer mosfet part is located within the case cutout, so only the upper part is problematic. I could very well install a larger sized heatsink on that lower mosfet part.

Should those heatsinks not be touching the back of the case (metal on metal)?

Where should I get the suitable mosfet heatsinks?

The photos are provided in attachments.

Thank you!



Sent from my iPhone using Tapatalk
 

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Riding on the edge
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@MisterMusculo I've been down this road when the Z was first released.

Those plates you mention for the back side of the mobo are definitely not heat sinks but rather insulators. (they are steel)
Their only purpose is to act as a stiffener to support the flimsy stock HS. I say flimsy only because it takes so much support from the back side to keep it in contact with mosfets etc.

I mounted a EK VRM/NB water block on my Z on day one and never looked back.
Ran my 9590 at 5117MHz for 4 1/2 years at 1.512v and max VRM temp of 55c (average 48.4c) under load 24 hr prime95 stable.

With the EK setup you simply remove those plates and leave them off as the water block is much more solid and does not need the support. Yours should be the same.
Plus side is no real reason to add HS to the back side after removing the insulting stiffener plates. A fan on the back side works wonders if temps are still an issue after adding the wb.
 

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Discussion Starter #3
@MisterMusculo I've been down this road when the Z was first released.



Those plates you mention for the back side of the mobo are definitely not heat sinks but rather insulators. (they are steel)

Their only purpose is to act as a stiffener to support the flimsy stock HS. I say flimsy only because it takes so much support from the back side to keep it in contact with mosfets etc.



I mounted a EK VRM/NB water block on my Z on day one and never looked back.

Ran my 9590 at 5117MHz for 4 1/2 years at 1.512v and max VRM temp of 55c (average 48.4c) under load 24 hr prime95 stable.



With the EK setup you simply remove those plates and leave them off as the water block is much more solid and does not need the support. Yours should be the same.

Plus side is no real reason to add HS to the back side after removing the insulting stiffener plates. A fan on the back side works wonders if temps are still an issue after adding the wb.


Thank you!

I guess it's safe then to just remove them and don't worry about it.

Another question: would I benefit anything from putting heatsinks on those vrm chokes (near the mosfets)?
 

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i can second the sandmans advice - from my own personal testing those backplates are of no thermal benefit and the board will not suffer or even gain anything from leaving them off. if u are concerned about temps add a fan to the back of the socket and over the vrm area as it will work wonders if u r indeed pushing that fx. nice job on the waterblocks as cvfz compatible stuff is getting hard to find these days. good luck with ur oc's
 

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Discussion Starter #5
i can second the sandmans advice - from my own personal testing those backplates are of no thermal benefit and the board will not suffer or even gain anything from leaving them off. if u are concerned about temps add a fan to the back of the socket and over the vrm area as it will work wonders if u r indeed pushing that fx. nice job on the waterblocks as cvfz compatible stuff is getting hard to find these days. good luck with ur oc's


Thanks!

I will try to push it to 5ghz. However it will take quite some time, I still have to order my parts, get a heat gun and all that stuff. I'm still waiting for a heatkiller set of screws, I'm in no rush I want to get it right.
 

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@MisterMusculo I've been down this road when the Z was first released.

Those plates you mention for the back side of the mobo are definitely not heat sinks but rather insulators. (they are steel)
Do you think this is the same case for the asus sabertooth 990fx? Because that would explain my terrible trials pushing to 5ghz I have been facing in 2018 lol! I hadn't taken them off yet, as I had assumed they were purposefully put there as a heatsink!
 

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I would just make sure to check the temps on what looks like doublers on the back of the board. Or maybe get small heatsinks for them as you can get stick on ones from Performance-pcs. Both of my CHV boards had thermal pads and those were aluminum on my boards so you should double check. You're pushing a lot of power through that at 4.8ghz for sure.
 

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Do you think this is the same case for the asus sabertooth 990fx? Because that would explain my terrible trials pushing to 5ghz I have been facing in 2018 lol! I hadn't taken them off yet, as I had assumed they were purposefully put there as a heatsink!
It may depend on which manf wb you use but this is right from EK.
Had to copy and paste text as OCN STILL doesn't allow me to upload a simple snip :(
Just an FYI, both my CHIV-F and CH5-Z plates were magnetic. Simply check yours.

"Details

EK-FB ASUS C5F-Z is a complete water cooling solution for ASUS® Crosshair V Formula(-Z) motherboard. This waterblock directly cools AMD® 990FX northbridge chip and power regulation (VRM / MOSFETs) module. It is medium-high to high flow water block design that can be easily used with systems using weaker water pumps.

Base of the waterblock is made of nickel plated electrolytic copper while the top is made of quality POM Acetal material and covered with laser cut stainless steel plate. The sealing is performed by quality rubber gaskets.



Water block is mounted with enclosed M2.5x4 DIN7985 screws and PVC washers. Preinstalled 2.1mm nickel plated brass screw-in standoffs allow for easy installation.

Enclosed thermal pad is used on voltage regulator module to improve cooling performance of the waterblock. On the northbridge please use any electrically non-conductive thermal grease, e.g. Gelid GC-Extreme.

The southbridge chip SB950 remains cooled by factory (ASUS®) provided heat-sink.

This product is intent to be run without the backplates. The stock backplates are made of steel anyway and don’t have practically any cooling surface. Their only job is to ensure even contact of the factory flimsy heat-pipe cooling system with the MOSFETs. Because the EK-FB ASUS C5F-Z waterblock is made out of hard electrolytic copper there is no need for such backplates."

Source: https://www.ekwb.com/shop/ek-fb-asus-c5f-z-acetal-nickel
 
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