(Partially)Passive Crossfire

samuelmorris · Post by **samuelmorris** » Mon May 12, 2008 5:08 pm

Hi again,
I've been using a pair of HD3870s in Crossfire for a month or two now, and have had about the level of success I was expecting getting the performance out of it. However, a few weeks back I suddenly noticed that the second card needed a very large fan speed increase to remain stable when it was being used - typically about 55-60%, and this is the stock cooler.
(The primary card uses the Asus gold flower cooler, which despite its looks cools quite well, and is actually pretty quiet, I'd guess 25-26dB).

Having recently made my CPU passive (E4300->3.15Ghz, T.R.U.E.) and been amazed by the results with low speed case fans I was considering giving it a go for at least one of the 3870s using an HR-03GT, since I had great success with an HR-03 on my old X1900XT.

My question is, what is it on the card that's requiring the extra fan speed - the temp of the core remains below 50 so surely that's nowhere near overheating - the Asus card doesn't even have RAMsinks, so I doubt the RAM is overheating - is it the Vregs? And if so, is what comes with the HR-03GT sufficient to cool these in a low airflow environment, and do they stick on well? Almost all of the RAMsinks for my first HR-03 fell off - that didn't harm performance in the slightest, but I fear heatsinkless Vregs could cause a bit of a problem!

Additionally, in a standard ATX environment, how might you use a pair of HR-03GTs? I have a PCI network card I need to keep in the bottom slot ideally...
Any ideas on how best to go about this would be much appreciated.
Hardware:
E4300 @ 3.15Ghz, 1.44V
Gigabyte X38-DS4
4x Corsair XMS2-PC6400 CAS4
Asus HD3870
Powercolor HD3870
NZXT Lexa
Scythe SFF21Fx2 @ 700rpm, Scythe Kaze White 120mm @ 800rpm [Sunbeam Rheobus]

Thanks in advance

Sam

thejamppa · Post by **thejamppa** » Mon May 12, 2008 10:27 pm

The other non-asus HD 3870 probably has stock cooler? If that is so, HD 3870 has separate ram and VRM coolers from the main cooler. When you remove the main cooler, card will still have VRM and ram coolers. You can easily then snap HR-03 GT or Accelero S1 on the 2nd card.

The asus has non reference cooler but it should have cross-heatsink on the VRMS so getting HR 30-GT wouldn't be a problem either.

Accerlro S1's would be cheaper and better in low fan situations than HR-03. However to use that in CF you will need slightly mody by the other S1 byt bending and cutting few aluminion fins slightly to make space for the CF connector. But its doable.

HR-03 GT has no such need though but its twice as expensive as S1.

Of course you could use S1 in bottom card and HR-03 GT in top card, allowing cross fire bridge also be used.

That is if your system allows S1 to be used in bottom card.

samuelmorris · Post by **samuelmorris** » Wed May 14, 2008 11:31 am

Thanks for the reply thejamppa.
It's interesting that you say the Accelero S1 coolers work better in low airflow environments, I hadn't even considered them. Cheap though they are, I'd sooner not have to do any bending or cutting with the heatsinks, however simple as I'm not really the most dextrous person in the world and will probably damage something I shouldn't in the process.

The S1 and HR-03GT combination is an interesting idea. However, one of the reasons I was considering two HR-03s is that I can't really have a large heatsink dangling down in the bottom slot - there's a PCI network card there that can't really go anywhere else. If the S1 is quite thin then that would be useful as there'll be a slot of 'breathing room' for the NIC - right now it's getting pretty toasty down there.

My airflow route is currently Front in, top in, side out, rear out. Unfortunately since I removed the dust filter from the side fan when I first had it converted to exhaust (and promptly lost it...

) putting a fan as intake causes nasty resonance with the clear side panel on my case, so the side fan has to be an exhaust. Is this a viable strategy for the S1/HR-03GT combo?

I also read from SPCR's article that for an X1950XT-X, and so presumably for an HD3870 as well, you need a fan for the S1. This could cause issues with regard to the network card at the bottom...

thejamppa · Post by **thejamppa** » Wed May 14, 2008 1:25 pm

X1950XT is hotter than HD 3870. AC has tested Accelero working passively with HD 3870 and 8800 GT. Of course you need good ventilation for that.

samuelmorris · Post by **samuelmorris** » Wed May 14, 2008 3:35 pm

Hehe, well there's a side exhaust 120mm fan right next to where the cards are, but it only runs at 700-800rpm ish. Would that be sufficient, or would I have to put a fan on the S1?

thejamppa · Post by **thejamppa** » Thu May 15, 2008 2:16 am

Side fan combine with exhaust fan and PSU's fan should be more than enough. Of ourse if there is space front you could move the side fan into front blowing to both cards. I just saw you had NZXT Lexa case. In bottom case has filtered space for 80mm intake, right? That should provide extra air flow. You could choose like Nexus 80mm in that.

samuelmorris · Post by **samuelmorris** » Mon May 26, 2008 7:54 am

Yeah, I was thinking of getting a pair of Nexus 80s to fill those slots. If you think it'll make sufficient difference I'll do it. One thing I've noticed, since going with a Corsair HX 520W, the reduced fan speed means it practically isn't an exhaust fan any more...

samuelmorris · Post by **samuelmorris** » Thu May 29, 2008 9:47 am

Well, after spending considerable time attaching an Accelero S1 rev2 to my HD3870, it no longer works. Removing the cooler again showed me why - the core has been cracked in the corner. Very disappointing considering the delicacy I used during the archaic installation procedure (plastic clips? come on). With no warranty on the card, and presumably no coverage from Arctic I'm left with a Â£150 paperweight.

Once again, I ignored my first instincts (to get an HR-03GT), and paid the price.

Fortunately I am still left with the Asus0 graphics card, which incidentally after undervolting the fan is completely silent anyway.

Gillian Seed · Post by **Gillian Seed** » Thu May 29, 2008 1:54 pm

Gutted.

Sorry to hear that!

samuelmorris · Post by **samuelmorris** » Thu May 29, 2008 3:38 pm

Indeed. I'm thinking "you get what you pay for" - the S1 is half the price of the HR-03. Now I know why that is. Oh well, off to ebay with it as a 'faulty' job. Might perhaps make me a tenner..

Vicotnik · Post by **Vicotnik** » Thu May 29, 2008 6:18 pm

Sorry about your card, samuelmorris.

Core crush is always a risk with exposed cores. I wonder if we will see IHSs on the GPUs in the future.

But I must point out that there's imho nothing wrong with the quality of the Accelero S1. I have used a few passive coolers in the past - not the HR-03 though, so I can't really compare the quality between the HR-03 and the S1.

What I have used are Zalman ZM80D-HP, BeQuiet! Polar Freezer and AeroCool VM-102. The mounting system of the S1 is far superior to those at least. For me the installation of the S1 was a 5 min job, not so with the other coolers listed.

My point is that you should not blame the S1 for your broken card. I think lack of experience on your part or just simple bad luck is to blame.