Overclocked ATi 4890s: GPU only or full cover?

[jdcook]

I'm planning on running 2 x 4890s for my new build. Full cover blocks seemed like overkill so I was looking at the Swiftech MCW60 which works well and is nice and cheap. But then you still have the RAM and mofsets to cool. I then saw the MCW60-4870 with the heat pipe. This seems ideal but it costs almost as much as an EK full cover block!

Question: Do I just suck it up and get the full cover blocks or is an MCW60 plus the MC14 ramsinks enough? I want to get a decent overclock out of reference design 4890s.

Thanks.

[SoulsCollective]

48xxs, whether 70s or 90s, run extremely hot VRM temps, which are barely kept in check by the stock coolers. Core-only waterblocks are certainly attractively priced, but they usually fail to cool the VRMs as well as the stock cooler, meaning that while the GPU core is better cooled, the VRM temps spiral out of control, limiting OCing. You can either McGuyver a solution, usually out of RAMsinks/cut up bits of heatsink/lots of fans, but it just looks messy IMHO. Better to go with full-cover blocks - you can generally get 50-75% of the value of the block back when on-selling the card, or it's even rumoured that the 5-series single-core cards will follow a similar layout to the 4-series, meaning you might even be able to reuse them.

[Altspacen]

I have 2 xspc full cover blocks on my 4890's. One of them just died and the other one is still having high VRM temps on the 3rd one. 1st VRM is the coolest, followed by 2nd which is about 10C higher and then the 3rd is horrendous. Possible mounting issue but I cannot have anyone relay to me the location of the VRMs as 1, 2, and 3 so I can see where my mounting issue is. Using the supplied thermal tape, should I be doing any different?

[tuanster1119]

Get some EK or Koolance blocks. They're a little pricier but they mount effortlessly and will keep your VRMs relatively in check. I tried the XSPC blocks and I ended up throwing it on Ebay. The lack of standoffs made it really difficult to get a proper mount and there are plenty of stories of people killing their cards because of this.

I can't speak for the Swiftech FC blocks since I haven't used them.

[Razrback16]

As someone who is running 2x4890s, here is my experienced take. I have full coverage blocks on both of mine. They do not cool the VRMs acceptably (at least in my book). I had my cards voltmodded but the VRMs got so hot the cards would lock up (130-150*C!!! -- granted this is in summer heat ~80*F in the computer room, but still ridiculous). At stock volts with the core clocks at 925MHz the core temps are good around 40-45*C load (and were about the same at 1GHz when the cards were voltmodded), and the VRMs run ~100*C load temps on both cards. It is not a mounting issue with mine, so I suspect it's just a lack of cooling capability on my blocks for the VRMs -- they need more cooling capacity.

My advice is this: Pick up a card with an aftermarket heatsink that has a nice big heatsink on the VRMs that is separate from the heatsink on the core -- Newegg sells a nice Powercolor model that has something like this. Mount a fan on top of the VRM sink and get a core-only block for the GPU. The RAM will be fine without sinks, but I would personally run sinks on them just for additional cooling. I would imagine active air on sinks will cool the VRMs better than the pathetic heat-pipe cooling on the full coverage blocks. That is the route I will go on my next cards.

[wondergod]

Also take into consideration that he'll be running 2 cards in xfire. The mw60 is a pain to setup in xfire, the full cover blocks make it a breeze with an SLI adapter. I personally use the EK blocks and like them.

[SNiiPE_DoGG]

I also vote fullcover blocks, when volting the GPU's up via software the VRM cooling is THE essential component

[the_dope_chaud]

My advice is this: Pick up a card with an aftermarket heatsink that has a nice big heatsink on the VRMs that is separate from the heatsink on the core -- Newegg sells a nice Powercolor model that has something like this. Mount a fan on top of the VRM sink and get a core-only block for the GPU. The RAM will be fine without sinks, but I would personally run sinks on them just for additional cooling. I would imagine active air on sinks will cool the VRMs better than the pathetic heat-pipe cooling on the full coverage blocks. That is the route I will go on my next cards.

Thats a great piece of advice !

I have a 4870 with mcw60, core temps are great, but as others have sait, its not the only concern. ddr5 gets very hot, but the issue here is the vrms. Zalman makes 2 aftermarket vrm coolers for 4870/90

http://www.zalman.co.kr/ENG/product/...ad.asp?idx=352

http://www.zalman.co.kr/ENG/product/...ad.asp?idx=335

Thermalright also has one in the works.

As some have said, f/c blocks can do the job, but some seem to not cool the vrms very effectively, I still need a fan on mine with zalman part, if not, when overvolted, it conks out when the vrm hit 110-120c.

[Altspacen]

The lack of standoffs made it really difficult to get a proper mount and there are plenty of stories of people killing their cards because of this.

I can't speak for the Swiftech FC blocks since I haven't used them.

Both of my 4890 full cover blocks came with standoffs, little red almost cardboard like ones.

[tuanster1119]

Both of my 4890 full cover blocks came with standoffs, little red almost cardboard like ones.

Those aren't standoffs. What you're talking about is a washer, which basically does nothing. A standoff goes between the card and the waterblock, and prevents over tightening the screws, which can lead to warping and killing the card.

[Altspacen]

Those aren't standoffs. What you're talking about is a washer, which basically does nothing. A standoff goes between the card and the waterblock, and prevents over tightening the screws, which can lead to warping and killing the card.

Well then what exactly is the point of having the said washer? Should I try to procure some plastic ones in their place?

[jdcook]

Well then what exactly is the point of having the said washer? Should I try to procure some plastic ones in their place?

The cardboard washers are for electrical isolation so reduce the likelihood of shorts.

As for my new build, again, thanks everybody for your input. I'm concerned by the reports of high VRM temps even with full cover blocks. What's the point then? I think I am going to try the Swiftech MCW60 with MC14 ramsinks and the Zalman ZM-RHS90 for the VRMs.

[Freonor]

I'm running my 4890 at 1000/1050 and VRM temp according to everest is 77C when I'm gaming, but I don't play any REALLY tough games... It's mostly WoW and CS when I find the time to game.

[Jamesrt2004]

imo' id get the stock cooler rip the copper heatsink bit off it so you still have the big red part that goes over memory+vrm's with then fan then get a normal gpu block..

[Mescalamba]

+1 for full cover .. VRM´s are hot as hell on this..

[Yozzman]

Just use the stock cooling for the VRM's and do a core only

Here is my HD4870:

[Blizzy]

Which block for the 4890 you guys think its better ?

Watercool GPUX² or Koolance ?

[mhar998]

definitely get full cover blocks

[jdcook]

What's great about this thread is the unanimity of the advice.

[Yozzman]

Hehehehe indeed :P

Depends also on the money u got i think...
Lot of money, go for the full cover...
If u dont have a lot of money, go for the core only
Advantage is that the block isnt made specially for the HD4890, it will fit ur next GPU also!

[SNiiPE_DoGG]

well with my EK 4890 fullcovers my card's VRMs top out at 55C under OCCT gpu test - FC has its perks (clocks 940/1000)

[Altspacen]

Well maybe the XSPC ones just don't' make the grade as far as cooling the VRM's go. Its a shame I can't seem to find 2 EK fullcovers in nickel. Maybe its just a seating problem, when I get my other 4890 back from RMA I'll let you guys know how mine works out if this thread is still active or if I don't forget.

[jdcook]

well with my EK 4890 fullcovers my card's VRMs top out at 55C under OCCT gpu test - FC has its perks (clocks 940/1000)

That's interesting. I like the EK full cover blocks a lot. I can afford them but I wasn't convinced it would be better on the VRMs as I've heard contrary things. Thanks.

[jdcook]

Well maybe the XSPC ones just don't' make the grade as far as cooling the VRM's go. Its a shame I can't seem to find 2 EK fullcovers in nickel. Maybe its just a seating problem, when I get my other 4890 back from RMA I'll let you guys know how mine works out if this thread is still active or if I don't forget.

Thanks.

[nafets]

If you are going the GPU only way, don't waste your time with the puny Zalman VRM heatsink. You really can't skimp on the VRMs with simple little aluminum heatsinks.

Sidewinder has both versions of Thermalright's new HD4870/90 VRM heatsinks. They look to be a pretty good match for WC'ing with a MCW60 on a HD4890. That combo is still more reasonably priced than a quality full cover GPU block...