Two Diamonds: ATI Radeon HD 2900 XT 1GB CrossFire Review @ Xbit-Labs

**MIG-31** · Sep 12, 2007, 07:33 AM

Review: Xbit-Labs
______________
We have last discussed the performance of multi-processor graphics solutions in the era of previous generation GPUs, such as Radeon X1000 and GeForce 7. Today we are going to return to this topic and cover it on a completely new level with the unique Diamond Multimedia graphics card: ATI Radeon HD 2900 XT.

Lelisevis · Sep 12, 2007, 08:10 AM

Hmm mixed feelings on this article. Very indepth and clearly a lot of time been took with it but comparing two cards in crossfire to a single card hardly seems appropriate.
Don't know how much time was taken trying to setup an SLI system but it seems to have been dismissed a little lightly. I've been running a pair of 8800GTS cards in SLI now since around may/june with an obvious increase in framerates. I know it's just a synthetic benchmark but I have no problems posting 14,000s and beyond in 3dmark06 so i'd imagine a pair of GTX's is going to add a few thousand too that.

Interesting read all the same

Mazuko · Sep 12, 2007, 02:31 PM

lelisevis they did mention that in crossfire mode the results are comprable to ONE 8800 Ultra in the conclusion section of the article.

I am actually one of those few who went out and bought dual diamond hd 2900 xt 1gb cards and am currently running them in my system now although with my current PS I am only able to use one 6pin pci-e cable per card.

I will however make one comment regarding the article that is not accurate. If you are ONLY USING the 6 pin pci power cable to power each card ATI AUTOMATICALLY downclocks both the memory speed and the core clock speed. This is not throttling like some people say as in every test I have done the clock speeds do not increase. My system using only one 6pin cable per card runs at 507Mhz core/514Mhz memory (downclocked by the system automatically due to power constraints). The stock speeds are 743mhz core/1100mhz memory).

Surprisingly though they actually even at this setting burn right through Lost Planet in dx10, Company of Heroes in dx10, and Medal of Honor Airborn demo like they weren't even there on max settings (well there is some lag up in lost planet at times especially in the cave....).

I called diamond tech support about this and here is what they told me.

"Sir, because you are not providing enough power to the cards with a single 6pin cable the drivers are detecting that not enough power is available to the card. What it is then doing is telling you via that popup you inquired about that it is downclocking the card in order to protect it and quite possibly your system, from damage. You could use adapaters to get the required power to your cards although I would not recommend it as the adapters currently available are poor quality, and no we do not offer power cable adapters for sale. I would however recommend upgrading your power supply."

So the cards only revert to normal speeds when providing BOTH the 6pin and the 8pin pci-e power cables to the cards.

I will also note I have not attempted to overclock my cards yet as I do not have the proper power supply to do such (currently running a BFG 800W with only 2x6pin and 0x8pin pci-e cables).

I have tried to use adapters and every single adapter I have purcahsed is not standard so won't fit the 8pin pci-e plug or it is an 8pin adapters but is for the motherboard, rather frustrating. I did however find a 6pin to an 8pin adapter, so I now would need to order a 2x4pin molex to 6pin pcie adapter so that I could run the cards although I have not looked at these yet. I will probably do that first because it is cheaper than an entirely new power supply though. So in otherwords with most current power supplies I would need 2 adapaters for each card to get them to work or a new power supply.

riles9262 · Sep 12, 2007, 02:37 PM

wow, that's insane. What rated power supply is required to run these things? I see xbit used 1k watt, but I would have thought that 800w would be sufficient

Zelig · Sep 12, 2007, 03:08 PM

That 800 watt should be alright, I'm guessing. They probably discourage adaptors to cover themselves from people trying to use 500 watt powmax PSUs.

Mazuko · Sep 13, 2007, 06:20 AM

The 800 watt PSU is sufficient it however only has 2x6pin pci-e cables, and the cards require (in total for both cards) 2x6pin and 2x8pin pci-e power cables hence the need for adapters or a new PS that has those 4 cables.

ChaosMinionX · Sep 13, 2007, 06:31 AM

Mazuko, highly suggest you get a PSU like mine, it has enough for both of those cards and more

Has 2 PCIE 8pin as well.

Sep 12, 2007, 07:33 AM	#1
MIG-31 HardwareHeaven News Mod Join Date: Dec 2002 Location: Nottingham,UK Posts: 56,819 Rep Power: 471 System Specs	Two Diamonds: ATI Radeon HD 2900 XT 1GB CrossFire Review @ Xbit-Labs Review: Xbit-Labs ______________ We have last discussed the performance of multi-processor graphics solutions in the era of previous generation GPUs, such as Radeon X1000 and GeForce 7. Today we are going to return to this topic and cover it on a completely new level with the unique Diamond Multimedia graphics card: ATI Radeon HD 2900 XT. __________________ Please Post Your News Submissions Here

Sep 12, 2007, 02:31 PM	#3
Mazuko DriverHeaven Senior Member Join Date: Aug 2003 Location: Fredericksburg, VA Posts: 1,008 Rep Power: 0 System Specs	lelisevis they did mention that in crossfire mode the results are comprable to ONE 8800 Ultra in the conclusion section of the article. I am actually one of those few who went out and bought dual diamond hd 2900 xt 1gb cards and am currently running them in my system now although with my current PS I am only able to use one 6pin pci-e cable per card. I will however make one comment regarding the article that is not accurate. If you are ONLY USING the 6 pin pci power cable to power each card ATI AUTOMATICALLY downclocks both the memory speed and the core clock speed. This is not throttling like some people say as in every test I have done the clock speeds do not increase. My system using only one 6pin cable per card runs at 507Mhz core/514Mhz memory (downclocked by the system automatically due to power constraints). The stock speeds are 743mhz core/1100mhz memory). Surprisingly though they actually even at this setting burn right through Lost Planet in dx10, Company of Heroes in dx10, and Medal of Honor Airborn demo like they weren't even there on max settings (well there is some lag up in lost planet at times especially in the cave....). I called diamond tech support about this and here is what they told me. "Sir, because you are not providing enough power to the cards with a single 6pin cable the drivers are detecting that not enough power is available to the card. What it is then doing is telling you via that popup you inquired about that it is downclocking the card in order to protect it and quite possibly your system, from damage. You could use adapaters to get the required power to your cards although I would not recommend it as the adapters currently available are poor quality, and no we do not offer power cable adapters for sale. I would however recommend upgrading your power supply." So the cards only revert to normal speeds when providing BOTH the 6pin and the 8pin pci-e power cables to the cards. I will also note I have not attempted to overclock my cards yet as I do not have the proper power supply to do such (currently running a BFG 800W with only 2x6pin and 0x8pin pci-e cables). I have tried to use adapters and every single adapter I have purcahsed is not standard so won't fit the 8pin pci-e plug or it is an 8pin adapters but is for the motherboard, rather frustrating. I did however find a 6pin to an 8pin adapter, so I now would need to order a 2x4pin molex to 6pin pcie adapter so that I could run the cards although I have not looked at these yet. I will probably do that first because it is cheaper than an entirely new power supply though. So in otherwords with most current power supplies I would need 2 adapaters for each card to get them to work or a new power supply. __________________ E-bay feedback: http://feedback.ebay.com/ws/eBayISAP...me=STRK:ME:UFS Last edited by Mazuko; Sep 12, 2007 at 02:39 PM.

Sep 12, 2007, 02:37 PM	#4
riles9262 Driverheaven brewmaster Join Date: Oct 2002 Location: British Columbia, Canada Posts: 4,842 Rep Power: 72 System Specs	wow, that's insane. What rated power supply is required to run these things? I see xbit used 1k watt, but I would have thought that 800w would be sufficient __________________ A beer a day keeps the doctor away.

Sep 12, 2007, 03:08 PM	#5
Zelig HardwareHeaven Extreme Member Join Date: Jun 2003 Location: Canada Posts: 3,187 Rep Power: 71 System Specs	That 800 watt should be alright, I'm guessing. They probably discourage adaptors to cover themselves from people trying to use 500 watt powmax PSUs. __________________ --

Sep 13, 2007, 06:20 AM	#6
Mazuko DriverHeaven Senior Member Join Date: Aug 2003 Location: Fredericksburg, VA Posts: 1,008 Rep Power: 0 System Specs	The 800 watt PSU is sufficient it however only has 2x6pin pci-e cables, and the cards require (in total for both cards) 2x6pin and 2x8pin pci-e power cables hence the need for adapters or a new PS that has those 4 cables. __________________ E-bay feedback: http://feedback.ebay.com/ws/eBayISAP...me=STRK:ME:UFS

Sep 12, 2007, 08:10 AM	#2
Lelisevis Howlin at the moon Join Date: Sep 2003 Posts: 1,663 Rep Power: 0	Hmm mixed feelings on this article. Very indepth and clearly a lot of time been took with it but comparing two cards in crossfire to a single card hardly seems appropriate. Don't know how much time was taken trying to setup an SLI system but it seems to have been dismissed a little lightly. I've been running a pair of 8800GTS cards in SLI now since around may/june with an obvious increase in framerates. I know it's just a synthetic benchmark but I have no problems posting 14,000s and beyond in 3dmark06 so i'd imagine a pair of GTX's is going to add a few thousand too that. Interesting read all the same

Sep 13, 2007, 06:31 AM	#7
ChaosMinionX USB 3 dot oh Join Date: Nov 2006 Location: Boston, MA Posts: 1,911 Rep Power: 47 System Specs	Mazuko, highly suggest you get a PSU like mine, it has enough for both of those cards and more Has 2 PCIE 8pin as well. __________________ ::Heatware:: How you can help DriverHeaven by using Digg!