Hi Guru's....
I have a couple of questions regarding a PSU that may not be putting out enough amps on the 12v rails. Here is my setup (yeah I know the PSU is undersized for this rig, but I just bought in 3 weeks ago and want to be sure that it's the problem before buying a better one!)
Dual Core Opteron 170 2.0Ghz overclocked to 2.7Ghz
Sapphire Radeon 4890 1GB Crossfired with XFX 4890 1GB
Asus A8R32-MVP Deluxe (allows x16 in dual mode for PCIe slots)
OCZ Fatal1ty 550w PSU with 25A on each of two 12V rails
And hey - no joking about my ancient CPU alongside dual 4890's ok!!
Anyway, at full load my PSU is pulling around 470w from the wall. From a wattage standpoint it seems my PSU is capable of handling this system. I dont get random reboots or crashes in games either. However, when benchmarking in Crysis I get a strange issue...
With Crossfire disabled I get around 20 FPS 1920x1080 2xAA High Settings
With Crossfire enabled I get around 38 FPS with the same settings..... but it only lasts for a few minutes before the FPS drops down to around 20 and stays there. Basically it seems like one of the cards just stops working in Crossfire mode. This does not happen in Metro 2033. I had Rivatuner running in the background and it showed GPU usage on both 4890's throughout the Crysis benchmark run even though the FPS fell to non Crossfire rates.
Does this sound like a "not enough juice" problem, perhaps on the 12v rails? I say this because each 4890 requires 2 6-pin PCIe connectors, but my PSU only has 2 available. I have to use molex to PCIe adapters for the other 2. I have tried switching around which card gets the dedicated PCIe connections, and even mixed them so each card gets 1 dedicated PCIe connection and 1 molex to PCIe adapter connection.
If this does indeed sound like my PSU isnt putting out enough power to run these cards, is there any value in getting an adapter that converts the usused 8-pin EPS connection to a PCIe connection - like this one:
http://www.frozencpu.com/products/86...27&id=Vp3q3qP4
Your help is appreciated!
I have a couple of questions regarding a PSU that may not be putting out enough amps on the 12v rails. Here is my setup (yeah I know the PSU is undersized for this rig, but I just bought in 3 weeks ago and want to be sure that it's the problem before buying a better one!)
Dual Core Opteron 170 2.0Ghz overclocked to 2.7Ghz
Sapphire Radeon 4890 1GB Crossfired with XFX 4890 1GB
Asus A8R32-MVP Deluxe (allows x16 in dual mode for PCIe slots)
OCZ Fatal1ty 550w PSU with 25A on each of two 12V rails
And hey - no joking about my ancient CPU alongside dual 4890's ok!!
Anyway, at full load my PSU is pulling around 470w from the wall. From a wattage standpoint it seems my PSU is capable of handling this system. I dont get random reboots or crashes in games either. However, when benchmarking in Crysis I get a strange issue...
With Crossfire disabled I get around 20 FPS 1920x1080 2xAA High Settings
With Crossfire enabled I get around 38 FPS with the same settings..... but it only lasts for a few minutes before the FPS drops down to around 20 and stays there. Basically it seems like one of the cards just stops working in Crossfire mode. This does not happen in Metro 2033. I had Rivatuner running in the background and it showed GPU usage on both 4890's throughout the Crysis benchmark run even though the FPS fell to non Crossfire rates.
Does this sound like a "not enough juice" problem, perhaps on the 12v rails? I say this because each 4890 requires 2 6-pin PCIe connectors, but my PSU only has 2 available. I have to use molex to PCIe adapters for the other 2. I have tried switching around which card gets the dedicated PCIe connections, and even mixed them so each card gets 1 dedicated PCIe connection and 1 molex to PCIe adapter connection.
If this does indeed sound like my PSU isnt putting out enough power to run these cards, is there any value in getting an adapter that converts the usused 8-pin EPS connection to a PCIe connection - like this one:
http://www.frozencpu.com/products/86...27&id=Vp3q3qP4
Your help is appreciated!
Facebook
Twitter