VRM cooling experience

I was trying to google if VRM cooling was useful or if my MB was just crappy and there was lots of discussions but no clear answers. So I wanted to make a post about my experience for anyone else out there with similar issues.

It all started when I wanted to see if my fairly late FX8320 had good OC in it. It went happily up to 4,2Ghz (didnt dare try higher) but I came across another issue. Thermal throtling. The kind of throtling that instantly drops the clock on all cores to 1,4Ghz and stays there for several seconds. With some googling I found out that this was actually not the CPU doing the throtling, CPU throtling is much more subtle "flickering" of lower clocks on random cores. The power circuitry on my MB was overheating. And even worse, this thermal throtling would occur even on default clocks in some situations like doing a handbrake transcoding or in that early level in crysis 3 where you have to destroy the defence tower.

My MB is a Asus M5A78L witch has a 140w 4+1 circuitry, a decent setup for light OC but the complete lack of cooling hurts the performance big time. Also a tower cpu cooler like my Zalman CNPS7 wont blow any air on the MOSFETs, unlike a stock cooler might.

So I was thinking about a proper MB (M5A is a 50€ board) but I wasnt excited about a complete rebuild so I dug into my drawers and found some old heatsinks from a GPU cooling kit, small glueable bits. So I glued them on my MOSFETs and someone gave an excellent advice of reversing the rear case fan which would then blow a good breeze at the MOSFETs.

So did it make a difference? I was thermally throtling on default clocks before and now I'm running a 4Ghz overclock with no realworld thermal throttling. the mentioned handbrake and crysis run without issues and only occasion of thermal throttling has been with a specific burn tests.

So I can recommend these steps to anyone with overheating VRMs.

Active VRM cooling won't help on a 4 phase board.

You need a 990FX sabertooth at least for a 8 cores.

All you did is buy yourself a little time. That board will fail no matter how much cooling you put to it. There is simply not enough power phases for an 8 core FX even at stock.
You do realize that your overclock puts you well above that 140w power phase, right? The more you overload the board, the shorter the lifespan, and no cooling in the world will stop that.

maha_x said:

I was trying to google if VRM cooling was useful or if my MB was just crappy and there was lots of discussions but no clear answers. So I wanted to make a post about my experience for anyone else out there with similar issues.

It all started when I wanted to see if my fairly late FX8320 had good OC in it. It went happily up to 4,2Ghz (didnt dare try higher) but I came across another issue. Thermal throtling. The kind of throtling that instantly drops the clock on all cores to 1,4Ghz and stays there for several seconds. With some googling I found out that this was actually not the CPU doing the throtling, CPU throtling is much more subtle "flickering" of lower clocks on random cores. The power circuitry on my MB was overheating. And even worse, this thermal throtling would occur even on default clocks in some situations like doing a handbrake transcoding or in that early level in crysis 3 where you have to destroy the defence tower.

My MB is a Asus M5A78L witch has a 140w 4+1 circuitry, a decent setup for light OC but the complete lack of cooling hurts the performance big time. Also a tower cpu cooler like my Zalman CNPS7 wont blow any air on the MOSFETs, unlike a stock cooler might.

So I was thinking about a proper MB (M5A is a 50€ board) but I wasnt excited about a complete rebuild so I dug into my drawers and found some old heatsinks from a GPU cooling kit, small glueable bits. So I glued them on my MOSFETs and someone gave an excellent advice of reversing the rear case fan which would then blow a good breeze at the MOSFETs.

So did it make a difference? I was thermally throtling on default clocks before and now I'm running a 4Ghz overclock with no realworld thermal throttling. the mentioned handbrake and crysis run without issues and only occasion of thermal throttling has been with a specific burn tests.

So I can recommend these steps to anyone with overheating VRMs.

Click to expand...

But on that CPU the stock turbo speed is 4.0 ghz. By overclock do you mean a non-turbo base overclock to 4.0 ghz?

I'm overclocking my CPU but I should be concerned about my MB's lifespan? Yeah, my MB is still crappy but it is adverticed as compatible with 8 core CPUs and has been running this configuration for years at stock speeds. There's lots of 4 phase boards like the Asrock extreme series, hard to believe none of them support 8 cores. Besides my MB only needs to make it till Ryzen comes out

Turbocore is broken in this mobo. For example I set the multipliers so that I get 4Ghz base and 4,2 turbo and it gives me 3,7Ghz flat, no turbo. I tried various configurations and sometimes it works, sometimes not. It also seems to turbo most of the time so I leave it off for consistency. Or maybe there's some complex rules for configuring the turbocore that I'm utterly unaware of.

It os not thermal throttling: the VRMs can't handle the load: so your CPU is running for [email protected]...

All those 4 phases board support 8 cores CPUs... at 1.4GHz throttling!

A proper MoBo for 8cores FX is $150.

A lot of guys around been there (Johan, Scotty, Mandrake, myself... among others).

You want to run a FX@stock, need a sabertooth or Crosshair IV, an 990FX M5a99 pro r2.0 might do.

You want to run it@4GHz+?
Sabertooth or CHIV.

The Gigabyte GA 990FXA UD3 might do, if you get the right revision(don't remenber which one though...).

Tír na nÓg said:

It os not thermal throttling: the VRMs can't handle the load: so your CPU is running for [email protected]...

All those 4 phases board support 8 cores CPUs... at 1.4GHz throttling!

A proper MoBo for 8cores FX is $150.

A lot of guys around been there (Johan, Scotty, Mandrake, myself... among others).

You want to run a FX@stock, need a sabertooth or Crosshair IV, an 990FX M5a99 pro r2.0 might do.

You want to run it@4GHz+?
Sabertooth or CHIV.

The Gigabyte GA 990FXA UD3 might do, if you get the right revision(don't remenber which one though...).

Click to expand...

This is reality, ma_hax. Technically, your board is compatible with the FX 8 core CPUs. It will boot and run Windows programs. That's what the motherboard manufacturers mean when they say the CPU is "compatible" with your motherboard. Yes, it is deceptive from the consumer's point of view but that is the way it is and if you had come to this forum before purchasing and asked the community's opinion on using that board with that CPU we would have alerted you to this issue. Lowering core voltage will generate less power draw and help the VRM area run cooler.

Having said all that, I disagree with Mr. Scott and would suggest at least trying some active cooling on the VRM area and on the backside or the socket. It may allow you to run the CPU at stock frequencies. The other thing you might also try, either by itself or together with some active VRM/socket cooling, is to lower the CPU core voltage. Oftentimes, you can cut the stock voltage a little and still be stable.

trents said:

Having said all that, I disagree with Mr. Scott and would suggest at least trying some active cooling on the VRM area and on the backside or the socket. It may allow you to run the CPU at stock frequencies. The other thing you might also try, either by itself or together with some active VRM/socket cooling, is to lower the CPU core voltage. Oftentimes, you can cut the stock voltage a little and still be stable.

Click to expand...

Temp isn't what kills the board/VRM, the over draw does.
No different than a CPU, temp doesn't kill those either, voltage does. Same principle applies.
Cool that VRM all you want, the over draw will kill it anyway.

The only thing you have going for you is the Asus brand is stout as your gonna get with the 760G chipset. I've done several sub zero overclocking on the M5A78L motherboard. I choose this board for zub zero only because of the cheap costs of it and if it died, no sweat.

Overclocking is a risk on any board, just higher risks on the 4+1 power phase.

8 cores 6100mhz and some change with 4+1. It can be done.
http://valid.canardpc.com/accq5v

Mr.Scott said:

Temp isn't what kills the board/VRM, the over draw does.
No different than a CPU, temp doesn't kill those either, voltage does. Same principle applies.
Cool that VRM all you want, the over draw will kill it anyway.

Click to expand...

I don't disagree with that but all I'm saying is it might enable him to run the CPU for as long as the board lasts if he cools the VRMs and socket backside.

- - - Updated - - -

ShrimpBrime said:

The only thing you have going for you is the Asus brand is stout as your gonna get with the 760G chipset. I've done several sub zero overclocking on the M5A78L motherboard. I choose this board for zub zero only because of the cheap costs of it and if it died, no sweat.

Overclocking is a risk on any board, just higher risks on the 4+1 power phase.

8 cores 6100mhz and some change with 4+1. It can be done.
http://valid.canardpc.com/accq5v

Click to expand...

Agreed. Asus does seem to build stouter boards than most in the same chispet family and price range.

Tír na nÓg said:

Active VRM cooling won't help on a 4 phase board.

You need a 990FX sabertooth at least for a 8 cores.

Click to expand...

I really hate seeing this repeated so much here.
You do not need a sabie for an 8 series to run well - I've used two 970a-UD3 boards that both overclock an fx8 to 4.5 on air and are half the price. As long as you get one of the revisions with the 8+2 phase you will be set.

rescuetoaster said:

As long as you get one of the revisions with the 8+2 phase you will be set.

Click to expand...

That's the point... The rev.

Quoting myself:
- - - Updated - - -

Tír na nÓg said:

You want to run a FX@stock, need a sabertooth or Crosshair IV, an 990FX M5a99 pro r2.0 might do.

You want to run it@4GHz+?
Sabertooth or CHIV.

The Gigabyte GA 990FXA UD3 might do, if you get the right revision(don't remenber which one though...).

Click to expand...

I've seen enough stories on both side of the aisle for the Giga boards to avoid them for an FX you want to OC. Yes, some folks have had success. And some have gotten an Asus board because the Giga board just wasn't cutting it. My M5A99FX Pro hit 4.5 GHz with a hex core on stock voltage, and it wasn't the price of the big cat or the CH. There are places to save money, but if you're going to OC an octo core FX the motherboard isn't one of them, IMO.

It's really simple. 8320 and 8350 are 125W parts and the board is rated for 140W output. It will run a 8 core FX just fine and has done so for years. Stock clocks, no throtling, no overdraw. However it is a design omission to not include any cooling for the VRMs which causes the board to throttle under heavy load. As I have found out, cooling does help.

Overclocking on the other hand can push the board beyond the rated power and impact lifetime, I know that. However there are many factor in this matter. Most notably my workloads include office work and gaming so I am hardly ever pushing the chip to max power and my MB is seeing very little time maxing the power circuitry. Also there's the quality of the chip. As the production process is expected to improve over time my fairly new 8320 might be a rebadged 8350. Im fairly confident I'll be running this setup through 2017 without a problem.

Stock 8350 can be way above 125w on load (compare with a 3960x, 130W TDP, 40W less on load than the 125W 8350...):
http://www.guru3d.com/articles-pages/amd-fx-8350-processor-review,7.html

Edit: of course, if you use your cpu mainly at idle, it is a non issue.

I believe an 8 core FX can hit 200+ watts when you start twisting its tail. That is enough to let the magic smoke out of your VRMs. Just sayin'.

maha_X, I'm also new to overclocking so these guys may want to correct me although I really dont think my situation applies to you. Often the temp sensors arent properly labeled which lead me to believe my VRM's were overheating, when it was actually my socket. I have a h100i AIO cooler so my CPU was fine, but I was noticing some throttling under heavy load. I put fans on my VRM and it didn't help AT ALL. Come to find out the stock cooler blows air down around the VRM and <ding ding> the socket as well. My AIO didn't provide that. I ended up dropping the stock cooler on the back of the mobo blowing down on my socket, got another 250mhz out of it. I was also using the Asus utility to do my overclock.... Garbage.... Now that I have my CPU, bus, NB, and RAM all SEMI dialed in, it's so much quicker it's unreal. Now your board is quite a bit different than mine. I'm running an 8320 on a M5A99FX Pro R2 board which at least has a 6+2 phase VRM. I'm not gonna lie, too much voltage is going to cool those VRM's. They just weren't built for that. I mean Ryzen is right around the corner so I don't see you killing it off pre-release but too much voltage and temp will be the demise of that mobo. The CPU is gonna be fine, they are troopers and people are tossing retarded voltages as these things... Just watch your temps until Ryzen comes out. Don't let it cook too hard.

My problems weren't mislabeled sensors. My last board (Asus) apparently had 6 different sensors, numbered 1-6. With no offer of a peek at their naming scheme. It wouldn't surprise me to find out they number them randomly in the Engineering department. Engineers are some strange dudes. LOL (two of my uncles were engineers)