Couple o' wonderings...

[kruppsy]

Just a couple of questions really...I can't find definitive answers anywhere, so you guys can hopefully shed some light.

First one. Whats the lifespan of thermal compound? Im running an oc'd Core2Duo with an Arctic Freezer Pro, the paste was pre-loaded on the heatsink if i remember rightly and its been going for the best part of 7 years I think. My temps aren't fluctuating massively but I have recently pushed the oc slightly so there was a bit of an increase. Should i re-apply, or only if i start getting silly temps? Currently its something like 27-32C idle, ~55C after gaming (thats about as much load as i give it these days). I know the temps are ok but want to keep the CPU as happy as possible if i decide to take the oc further(which i probably will).

Second one. I have a 1GB 6950. If I was to crossfire down the line and say pick up the 2GB version (1GBs are quite rare now), what will the cards run at memory wise in crossfire combined? 1GB only, 1GB + 1GB (taking the lower spec) or 1 GB + 2GB? I assumed combining two different memory versions of the same card will work anyway? This isn't really going to make a difference to any choices I make, I was just interested.

Cheers.

 

[Karnor00]

Thermal compound doesn't generally go off once it's applied. So unless your temperatures start getting very high (and yours look fine atm) then I wouldn't worry about changing it.

As for mixing GPU's with different VRAM, according to NVidia the answer is no : http://www.geforce.co.uk/hardware/technology/sli/faq#c19

Furthermore, although NVidia say that you can mix and match cards between vendors, according to Tom's Hardware, in practice this isn't always the case : http://www.tomshardware.co.uk/radeon-geforce-stutter-crossfire,review-32256-15.html

 

[vanthus]

Thermal compound.
I don't think there is a definitive life span of thermal paste,probably depends on your uses,how well it was applied and the quality of the compound.When temps begin to rise of course,it's an obvious sign the compound might need to be replaced,though there could be another reason.
Vram.
I've done quite a bit of searching in the past about this myself,this seems to be the opinion of most sources.
unlike Nvidia in SLI,different Vram cards should work in crossfire.
Two 1GB cards in crossfire will still only produce 1GB of Vram,this seems pretty conclusive.
One 1GB + one 2GB will still only produce 1GB of Vram,there is some disagreement with that.

 

[kruppsy]

Cheers guys.

Dug this out...

http://support.amd.com/us/kbarticles/Pages/AMDCrossFireFAQ.aspx

Supports you vanthus. Now hit with the realisation that my P5K mobo, because of its early PCI slots, cant cope with modern GPUs in Crossfire If i want to do it i'll need to upgrade a lot more than I'd hoped...ah well...

EDIT: hmmm conficting info on this as well, P5K (advertised as Crossfire compatible), P35 chipset, 1 PCIe x16 + 1 PCIe x4/x1. Will this support 6950s? Or will performance be hindered (not worth it)?

 

[tom_gr7]

kruppsy

Are you gaming on one screen? if so just stick with a single powerful gpu instead of two together. I went for two 580's, which increased my power draw, heat output and noise. All for a load more FPS. Due top the 6950 being last amd generation. It would be better (if you wanted to upgrade) to go for a single 7950 or 7970 if you wanted to stay with the amd camp.

But, then you have to consider any bottlenecks that may occur, as the cpu wont be anywhere near as current as the gpu. I think corfate had dramas on his old amd cpu when he whacked in a 7850. I will try and get him to confirm.

 

[Corfate]

Hello, Tom has summoned me!

The bottleneck i had wasn't with the 7850, as the AMD CPU was capable of running it fine, it was when i stuck a 670 into the mix i got trouble haha.

I was running a 670, 8GB RAM and a dual core AMD CPU. In BF3, you'd expect a 670 to blitz it, ultra everything, 60FPS easy. With the AMD CPU i could only just run BF3 on Med settings, as the lag i got was unbelievable. The CPU couldn't cope basically. Then when i stuck a quad core i5 OC'ed at 4.5ghz into the rig, it now runs everything on max, fully turned up, 60fps easy.

Basically, don't skimp on important items. The CPU and GPU need to be balanced

Hope this helps, if it can haha!

 

[kruppsy]

Always helpful! Cheers guys

Yea tom it's just one screen, a 19"! My pc is a continual evolving process and cost effectiveness went out the window long ago! I like it being up to date(ish!) but also a bit different as well if that makes sense. I wouldn't mind too much about the pitfalls of crossfire just so I can mess about with a crossfire set up. My plan was to wait a year and do a bit of an overhaul, by putting in a 1155 mobo, definitely a monitor! etc but running the crossfire 6950s still. I paid 70 quid for my 6950, crossfired should give me 7970 performance? For £140, I'd be happy with that tbh even if by the time I get round to it, it's all old hat. I like the tinkering side as much as the performance, maybe I'm odd?!